Stroke Specific Quality of Life Scale (SS-QOL)

Purpose

The StrokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. Specific Quality Of Life scale (SS-QOL) is a patient-centered outcome measure intended to provide an assessment of health-related quality of life (HRQOL) specific to patients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain..

In-Depth Review

Purpose of the measure

The StrokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. Specific Quality Of Life scale (SS-QOL) is a patient-centered outcome measure intended to provide an assessment of health-related quality of life specific to patients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain..

Available versions

The SS-QOL was published and validated in 1999 by Williams, Weinberger, Harris, and Clark.

Features of the measure

Items:
Scale domains and items were derived from a series of interviews with post-stroke patients (Williams et al. 1999a).

Patients must respond to each question of the SS-QOL with reference to the past week. It is a self-report scale containing 49 items in 12 domains:

• Mobility (6 items)
• Energy (3 items)
• Upper extremity function (5 items)
• Work/productivity (3 items)
• Mood (5 items)
• Self-care (5 items)
• Social roles (5 items)
• Family roles (3 items)
• Vision (3 items)
• Language (5 items)
• Thinking (3 items)
• Personality (3 items)

Subscales:
Energy, Upper extremity function, Work/productivity, Mood, Self-care, Social roles, Family roles, Vision, Language, Thinking, and Personality.

Equipment:
Only a pencil and the test are needed.

Training:
No training is required, as the SS-QOL is intended to be self-administered. One study suggests that the scale can be administered to patients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. reliably over the telephone (Williams, Redmon, Saul & Weinberger, 2000).

Time:
It takes approximately 10-15 minutes to complete the SS-QOL scale.

Scoring:
Items are rated on a 5-point Likert scaleLikert scaling is one type of response to items in a questionnaire or tool. For example, Likert scaling would have you rate an item such as “I am satisfied with the care I received” on a scale using a 1-to-5 response scale where:
• 1 = strongly disagree
• 2 = disagree
• 3 = undecided
• 4 = agree
• 5 = strongly agree
You will find various options and scaling methods for the number of response choices (1-to-7, 1-to-9, 0-to-4). Odd-numbered scales usually have a middle value that is labelled Neutral or Undecided. Some tools used forced-choice Likert scaling with an even number of responses and no middle neutral or undecided choice.. There are 3 different response sets (see table below). Patients must respond to each item using the corresponding response set as indicated on the scale (Williams et al. 1999a). For example, the item “did you have any trouble doing daily work around the house?” requires response set 2, which ranges from “couldn’t do it at all” to “no trouble at all”.

Response Sets:

1. Total help	2. A lot of help	3. Some help	4. A little help	5. No help needed
1. Couldn’t do it at all	2. A lot of trouble	3. Some trouble	4. A little trouble	5. No trouble at all
1. Strongly agree	2. Moderately agree	3. Neither agree nor disagree	4. Moderately disagree	5. Strongly disagree

Higher scores indicate better functioning. The SS-QOL yields both domain scores and an overall SS-QOL summary score. The domain scores are unweighted averages of the associated items while the summary score is an unweighted average of all twelve domain scores (Williams et al. 1999b).

Alternative forms of SS-QOL

• The StrokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. and AphasiaAphasia is an acquired disorder caused by an injury to the brain and affects a person’s ability to communicate. It is most often the result of stroke or head injury.
  An individual with aphasia may experience difficulty expressing themselves when speaking, difficulty understanding the speech of others, and difficulty reading and writing. Sadly, aphasia can mask a person’s intelligence and ability to communicate feelings, thoughts and emotions. (The Aphasia Institute, Canada) Quality Of Life Scale (SAQOL-39 – Hilari, Byng, Lamping, & Smith, 2003). Developed from the SS-QOL for use in patients with long-term aphasiaAphasia is an acquired disorder caused by an injury to the brain and affects a person’s ability to communicate. It is most often the result of stroke or head injury.
  An individual with aphasia may experience difficulty expressing themselves when speaking, difficulty understanding the speech of others, and difficulty reading and writing. Sadly, aphasia can mask a person’s intelligence and ability to communicate feelings, thoughts and emotions. (The Aphasia Institute, Canada), the SAQOL-39 has four subdomains (Physical, Psychosocial, Communication, and Energy). It is an interview-administered self-report scale. It is comprised of items from the SS-QOL that have been modified to ensure they are appropriate for use in individuals with aphasiaAphasia is an acquired disorder caused by an injury to the brain and affects a person’s ability to communicate. It is most often the result of stroke or head injury.
  An individual with aphasia may experience difficulty expressing themselves when speaking, difficulty understanding the speech of others, and difficulty reading and writing. Sadly, aphasia can mask a person’s intelligence and ability to communicate feelings, thoughts and emotions. (The Aphasia Institute, Canada). The SAQOL-39 has four additional items that were added to increase the content validityRefers to the extent to which a measure represents all aspects of a given social concept. Example: A depression scale may lack content validity if it only assesses the affective dimension of depression but fails to take into account the behavioral dimension.
  of the scale with this population. These four items focus on the difficulties with understanding speech, issues with decision-making, and the impact of language difficulties on family and social life.

Hilari et al. (2003) reported that the SAQOL-39 has good acceptability, adequate to excellent internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. (Cronbach’s alphas ranging from 0.74 to 0.94), excellent test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society).
(intraclass correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases - for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases - for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
coefficient = 0.89 to 0.98), and poor to excellent construct validityReflects the ability of an instrument to measure an abstract concept, or construct. For some attributes, no gold standard exists. In the absence of a gold standard , construct validation occurs, where theories about the attribute of interest are formed, and then the extent to which the measure under investigation provides results that are consistent with these theories are assessed.
(corrected domain-total correlations, r = 0.38 to 0.58; convergent, r = 0.55 to 0.67; discriminant, r = 0.02 to 0.27 validityThe degree to which an assessment measures what it is supposed to measure.
). Further research is needed to confirm its psychometric properties and to determine its appropriateness as a clinical outcome measure.

Client suitability

Can be used with:

• Individuals with mild or moderate strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain..

Should not be used in:

• Patients without strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain.. The SS-QOL was developed and validated specifically for individuals with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. and has been examined for use in this population only.
• Severe strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. populations. The SS-QOL has not yet been tested among patients with severe strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain..
• Should be used with caution in patients with aphasiaAphasia is an acquired disorder caused by an injury to the brain and affects a person’s ability to communicate. It is most often the result of stroke or head injury.
  An individual with aphasia may experience difficulty expressing themselves when speaking, difficulty understanding the speech of others, and difficulty reading and writing. Sadly, aphasia can mask a person’s intelligence and ability to communicate feelings, thoughts and emotions. (The Aphasia Institute, Canada). Although the modified version of the scale, the SAQOL-39, has been validated for use in patients with long-term aphasiaAphasia is an acquired disorder caused by an injury to the brain and affects a person’s ability to communicate. It is most often the result of stroke or head injury.
  An individual with aphasia may experience difficulty expressing themselves when speaking, difficulty understanding the speech of others, and difficulty reading and writing. Sadly, aphasia can mask a person’s intelligence and ability to communicate feelings, thoughts and emotions. (The Aphasia Institute, Canada), it is a relatively new measure that requires further psychometric testing.
• Patients who require a proxy to complete. A study by Williams et al. (2006) compared proxy ratings of the SS-QOL to patient self administration in 225 patient-proxy pairs. Proxies rated all domains of SS-QOL lower than the patients. The intraclass correlation coefficient (ICC)Intraclass correlation (ICC) is used to measure inter-rater reliability for two or more raters. It may also be used to assess test-retest reliability. ICC may be conceptualized as the ratio of between-groups variance to total variance. for each domain ranged from poor (r = 30 for role function) to adequate (r = 0.59 for physical function). Proxy overall SS-QOL score was also rated lower than the patient score (3.7 versus 3.4) with an ICC of r = 0.41. It is recommended that information obtained from proxy respondents be treated as supplementary rather than substantive and that use of proxy be restricted to individuals either living with or in daily contact with the patient (Snow, Cook, Lin, Morgan & Magaziner, 2005; Muus, Petzold & Ringsberg, 2009).
• For patients who require a proxy, the StrokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. Impact Scale is a more reliable and valid measure of HRQOL (Duncan, Lai, Tyler, Perera, Reker, & Studenski, 2002).

In what languages is the measure available?

• Danish (SS-QOL-DK): translated Muus & Ringsberg, 2005 and validated Muus, Williams & Ringesberg, 2007.
• German: translated Ewart & Stucki, 2007 and initial validation study completed Ewart & Stucki, 2007. The initial validation study revealed validityThe degree to which an assessment measures what it is supposed to measure.
  of the total SS-QOL German score, however, some subscales (Energy, Mood and Thinking) were not validated. Further research is required.

Summary

What does the tool measure?	Health related quality of life
What types of clients can the tool be used for?	The SS-QOL was developed for use in patients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain..
Is this a screeningTesting for disease in people without symptoms. or assessment tool?	Assessment.
Time to administer	Approximately 10-15 minutes to complete.
Versions	The StrokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. and AphasiaAphasia is an acquired disorder caused by an injury to the brain and affects a person’s ability to communicate. It is most often the result of stroke or head injury. An individual with aphasia may experience difficulty expressing themselves when speaking, difficulty understanding the speech of others, and difficulty reading and writing. Sadly, aphasia can mask a person’s intelligence and ability to communicate feelings, thoughts and emotions. (The Aphasia Institute, Canada) Quality Of Life Scale (SAQOL-39)
Other Languages	Translated and validated in Danish. Translated in German.
Measurement Properties
ReliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of “true” variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to “noise” in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .	Internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency.: One study examined the internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. of the SS-QOL and found that the internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. ranged from adequate (for work/productivity subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society). ) to excellent (for self-care). Test-retest: One study examined the test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society). of the SS-QOL and found excellent test-retest. Inter-rater: One study examined the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept. of the SS-QOL and found excellent inter-rater.
ValidityThe degree to which an assessment measures what it is supposed to measure.	Criterion: Predictive: The SS-QOL summary score significantly predicted overall post-stroke health-related quality of life. Construct: Convergent: Most domains of the SS-QOL correlate with the Barthel Index, the Beck DepressionIllness involving the body, mood, and thoughts, that affects the way a person eats and sleeps, the way one feels about oneself, and the way one thinks about things. A depressive disorder is not the same as a passing blue mood or a sign of personal weakness or a condition that can be wished away. People with a depressive disease cannot merely “pull themselves together” and get better. Without treatment, symptoms can last for weeks, months, or years. Appropriate treatment, however, can help most people with depression. Inventory, and subscales of the SF-36.
Floor/Ceiling Effects	One study reported ceiling effects exceeding 20% in 10 out of 12 domains of the SS-QOL, and a floor effectThe floor effect is when data cannot take on a value lower than some particular number. Thus, it represents a subsample for whom clinical decline may not register as a change in score, even if there is worsening of function/behavior etc. because there are no items or scaling within the test that measure decline from the lowest possible score. See also “ceiling effect.” of 24% in the Energy domain. Floor or ceiling effectA ceiling effect occurs when test items aren’t challenging enough for a group of individuals. Thus, the test score will not increase for a subsample of people who may have clinically improved because they have already reached the highest score that can be achieved on that test. In other words, because the test has a limited number of difficult items, the most highly functioning individuals will score at the highest possible score. This becomes a measurement problem when you are trying to identify changes – the person may continue to improve but the test does not capture that improvement. Example: A memory test that assesses how many words a participant can recall has a total of five words that each participant is asked to remember. Because most individuals can remember all five words, this measure has a ceiling effect. See also “floor effect.” exceeding 20% are typically considered poor.
Does the tool detect change in patients?	One study found that the SS-QOL had only a moderate ability to detect change in patients between 1 and 3 months post-stroke. A subsequent study involving an alternative language version of the SS-QOL, found a small to moderate ability to detect change in patients between 3 and 12 month post-stroke. In a later study, the minimal clinically detectable difference for the mobility, self-care and upper extremity function subscales was defined as a mean change in score of at least 1.5, 1.2 and 1.2 respectively.
Acceptability	Further investigation on the reliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of “true” variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to “noise” in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest . , validityThe degree to which an assessment measures what it is supposed to measure. , and sensitivitySensitivity refers to the probability that a diagnostic technique will detect a particular disease or condition when it does indeed exist in a patient (National Multiple Sclerosis Society). See also “Specificity.” of the SS-QOL is required with larger numbers of subjects. This measure has not been tested in severely affected patients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain.. For patients with aphasiaAphasia is an acquired disorder caused by an injury to the brain and affects a person’s ability to communicate. It is most often the result of stroke or head injury. An individual with aphasia may experience difficulty expressing themselves when speaking, difficulty understanding the speech of others, and difficulty reading and writing. Sadly, aphasia can mask a person’s intelligence and ability to communicate feelings, thoughts and emotions. (The Aphasia Institute, Canada), the SAQOL-39 is a more suitable version of the measure, however, it is a relatively new measure, which requires further psychometric testing. The scale is not suitable for use by proxy.
Feasibility	No training is required for the SS-QOL as the measure is intended to be completed by self-report. The measure is simple to score and is based on a 5-point Likert scaleLikert scaling is one type of response to items in a questionnaire or tool. For example, Likert scaling would have you rate an item such as “I am satisfied with the care I received” on a scale using a 1-to-5 response scale where: • 1 = strongly disagree • 2 = disagree • 3 = undecided • 4 = agree • 5 = strongly agree You will find various options and scaling methods for the number of response choices (1-to-7, 1-to-9, 0-to-4). Odd-numbered scales usually have a middle value that is labelled Neutral or Undecided. Some tools used forced-choice Likert scaling with an even number of responses and no middle neutral or undecided choice..
How to obtain the tool?	Click here to find a copy of the SS-QOL.

Psychometric Properties

Overview

The StrokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. Specific Quality of Life Scale (SS-QOL) is a new scale and has not been well studied. It has not been tested among severe strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. populations. To our knowledge, the creators of the SS-QOL have personally gathered the majority of psychometric data that are currently published on the scale. Further investigation on the reliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of "true" variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to "noise" in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .
, validityThe degree to which an assessment measures what it is supposed to measure.
, and sensitivitySensitivity refers to the probability that a diagnostic technique will detect a particular disease or condition when it does indeed exist in a patient (National Multiple Sclerosis Society). See also "Specificity."
of the SS-QOL is required with larger numbers of subjects.

Floor and Ceiling Effects

Czechowsky and Hill (2002) examined the SS-QOL and reported ceiling effects exceeding 20% in 10 out of 12 domains of the SS-QOL, and a ceiling effects exceeding 20% are typically considered poor.

Reliability

Internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency.:
Williams et al. (1999a) examined the internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. of the SS-QOL in 34 individuals with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. and found that Cronbach’s alpha ranged from adequate (alpha = 0.75 for work/productivity subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society).
) to excellent (alpha = 0.89 for self-care), suggesting that the SS-QOL has a strong internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency..

Test-retest:
In a study by Williams et al. (2000), the SS-QOL was administered by a trained interviewer to 47 strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. survivors at baseline and again within 2 hours of the initial interview. SS-QOL scores were highly correlated (r = 0.92), showing excellent test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society).
.

Inter-rater:
The SS-QOL was also administered by a trained interviewer to 24 strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. survivors and then a second trained interviewer re-administered the SS-QOL within 2 hours of the first interview. SS-QOL scores were highly correlated (r = 0.92), demonstrating excellent inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the SS-QOL.

Validity

Criterion:
Predictive:
Williams et al. (1999b) administered the SS-QOL to a total of 71 patients 1-month post-ischemic strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain.. Multivariate analysis showed that the SS-QOL summary score significantly predicted overall post-stroke health-related quality of life (HRQOL) (OR = 2.97). When scores were examined on the domain level, however, only one domain, Family Roles, was significantly different between groups, with higher scores in those patients with better overall HRQOL.

Construct:
Convergent:
Williams et al. (1999a) examined the validityThe degree to which an assessment measures what it is supposed to measure.
of the SS-QOL in 34 survivors of strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. and reported that most domains of the SS-QOL correlated with the Barthel Index, Beck DepressionIllness involving the body, mood, and thoughts, that affects the way a person eats and sleeps, the way one feels about oneself, and the way one thinks about things. A depressive disorder is not the same as a passing blue mood or a sign of personal weakness or a condition that can be wished away. People with a depressive disease cannot merely "pull themselves together" and get better. Without treatment, symptoms can last for weeks, months, or years. Appropriate treatment, however, can help most people with depression.
Inventory, and subscales of the SF-36. The Energy, Family Roles, Mobility and Work/Productivity domains were significantly associated with corresponding subscales on the SF-36. Total SS-QOL score correlated excellently with the overall SF-36 health status rating (r = 0.65). The self-care domain was adequately correlated with the Barthel Index (r = 0.45). Upper Extremity Function showed a positive but poor relationship with the Barthel Index and the National Institutes of Health StrokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. Scale Upper Extremity score (r = 0.18).

However, in this study, a few domains did not show a significant relationship with their corresponding measures. Scores in the Language and Thinking domains were not associated with selected items from the National Institutes of Health StrokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. Scale (r = 0.00 and r = 0.10 respectively). This most likely occurred because patients with language and cognitive deficits were excluded, i.e., there were no patients with a score > 1 on these items. Furthermore, the SS-QOL Social Roles domain was not associated with the SF-36 Social Functioning subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society).
score (r = 0.01). Finally, the Vision domain of the SS-QOL did not correlate with the National Institutes of Health StrokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. Scale Visual Field and Ocular Movement scores (r = 0.11).

Responsiveness

Williams et al. (1999a) examined the standardized effect sizeEffect size (ES) is a name given to a family of indices that measure the magnitude of a treatment effect. Unlike significance tests, these indices are independent of sample size. The ES is generally measured in two ways: as the standardized difference between two means, or as the correlation between the independent variable classification and the individual scores on the dependent variable. This correlation is called the “effect size correlation”.
scores for the interval between 1 and 3 months post-stroke in 34 individuals with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain.. Effect sizes ranged from small (ES = 0.20 for the personality domain) to large (ES = 0.83 for the social roles domain). One half of the SS-QOL domains demonstrated less than moderate effect sizes. The ‘amount of help’ response set appeared to lack responsivenessThe ability of an instrument to detect clinically important change over time.
. The results of this study demonstrate that the SS-QOL has only adequate responsivenessThe ability of an instrument to detect clinically important change over time.
.

Muus et al. (2011) investigated the responsivenessThe ability of an instrument to detect clinically important change over time.
of the Danish language version of the SS-QOL (SSQOL-DK). Patients were assessed at 3 and 12 months following strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain.. Small standardized effect sizes were found for all domains (-0.03-0.40), except the social roles domain which demonstrated moderate standardized effect sizeEffect size (ES) is a name given to a family of indices that measure the magnitude of a treatment effect. Unlike significance tests, these indices are independent of sample size. The ES is generally measured in two ways: as the standardized difference between two means, or as the correlation between the independent variable classification and the individual scores on the dependent variable. This correlation is called the “effect size correlation”.
(-0.53).

Lin, Fu, Wu & Hsieh (2011) examined the minimal clinically important difference (CID)Clinically Important Difference (CID) is the smallest change in a measure’s score that is perceived significant by a patient or healthcare professional., of the mobility, self-care and upper extremity function subscales of the SS-QOL. The study included 74 patients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. receiving rehabilitation and the SS-QOL was administered at baseline and at 3 weeks. The MCID ranges for the mobility, self-care and upper extremity function subscales were 1.5 – 2.4, 1.2 – 1.9, and 1.2 – 1.8 respectively. The results of the study indicate that mean change of score on the mobility, self-care and upper extremity function subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society).
should reach 1.5, 1.2 and 1.2, respectively, in order for change to be interpreted as clinically meaningful.

References

• Czechowsky, D., Hill, M. D. (2002). Neurological Outcome and Quality of Life after Stroke due to Vertebral Artery Dissection. Cerebrovascular Diseases, 13, 192-197.
• Duncan, P. W., Lai, S. M., Tyler, D., Perera, S., Reker, D. M., Studenski, S. (2002). Evaluation of proxy responses to the Stroke Impact Scale. Stroke, 33, 2593-2599.
• Ewart, T. & Stucki, G, (2007). Validity of the SS-QOL in Germany and in survivors of hemorrhagic or ischemic stroke. Neurorehabilitation and Neuro Repair, 21, 161-168.
• Hilari, K., Byng, S., Lamping, D. L., Smith, S. C. (2003). Stroke and Aphasia Quality of Life Scale-39 (SAQOL-39): Evaluation of acceptability, reliability, and validity. Stroke, 34, 1944-1950.
• Lin, K-C., Fu, T., Wu, C-Y. & Hsieh, C-J. (2011). Assessing the stroke-specific quality of life for outcomes measurement in stroke rehabilitation: Minimal detectable change and clinically important difference. Health and Quality of Life Outcomes, 9, 5. Retrieved April 25, 2012 from Sage Journals database.
• Muus, I., Christensen, D., Petzold, M., Harder, I., Johnsen, S.P., Kirkevold, M., Ringsberg, K.C. (2011). Responsiveness and sensitivity of the Stroke Specific Quality of Life Danish version. Disability and Rehabilitation, 33(25-26), 2425-2433.
• Muus, I., Petzold, M. & Ringsberg, K.C. (2009). Health-related quality of life after stroke: Reliability of proxy responses. Clinical Nursing Research, 18(2), 103-118.
• Muus, I., Ringsberg, K. C. (2005). Stroke Specific Quality of Life Scale: Danish adaptation and a pilot study for testing psychometric properties. Scand J Caring Sci, 19, 140-147.
• Muus, I., Williams, L.S. & Ringsberg, K.C. (2007). Validation of the Stroke Specific Quality of Life Scale (SS-QOL): Test of reliability and validity of the Danish version (SS-QOL-DK). Clinical Rehabilitation, 21, 620-627.
• Snow, A.L., Cook, K.F., Lin, P.S., Morgan, R.O. & Magaziner, J. (2005). Proxies and other external raters: Methodological considerations. Health Services Research, 40(5), 1976-1693.
• Williams, L. S., Weinberger, M., Harris, L. E., Clark, D. O., Biller, J. (1999a). Development of a stroke-specific quality of life scale. Stroke, 30(7), 1362-1369.
• Williams, L. S., Weinberger, M., Harris, L. E., Biller, J. (1999b). Measuring quality of life in a way that is meaningful to stroke patients. Neurology, 53, 1839-1843.
• Williams, L. S., Redmon, G., Saul, D. C., Weinberger, M. (2000). Reliability and telephone validity of the Stroke-specific Quality of Life (SS-QOL) scale. Stroke, 32, 339-b.
• Williams, L. S., Bakas, T., Brizendine, E., Plue, L., Tu, W., Hendrie, H., Kroenke, K. (2006). How valid are family proxy assessments of stroke patients’ health-related quality of life? Stroke, 37, 2081-2085.

See the measure

Please click here for a copy of the Stroke-Specific-Quality-of-Life-Scale (SS-QOL).