Purpose
The DOC screen is a screening tool that can be used to identify individuals at high risk of depression, obstructive sleep apnea and cognitive impairment following a stroke.
In-Depth Review
Purpose of the measure
The DOC screen is a screeningTesting for disease in people without symptoms.
tool that identifies individuals at high risk of 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.
, obstructive sleep apnea and cognitive impairment following a 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 DOC screen was developed by Swartz et al. and was first published in 2013. The tool was developed by combining and modifying three existing validated brief screens, the 2-item Patient Health Questionnaire (PHQ-2), the STOP questionnaire and a 10-point version of the Montreal Cognitive Assessment (MoCA).
Features of the measure
Items:
The DOC screen comprises three screeningTesting for disease in people without symptoms.
tests:
DOC – Mood (PHQ-2)
This test comprises two items with the purpose of screeningTesting for disease in people without symptoms.
for 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.
. The test evaluates the degree to which an individual has experienced depressed mood and anhedonia over the past two weeks.
DOC – Apnea (STOP Questionnaire)
This test comprises four items with the purpose of screeningTesting for disease in people without symptoms.
for obstructive sleep apnea: snoring, tiredness during daytime, breathing interruption during sleep, and hypertension.
DOC – Cog (10-point version of the MoCA)
This test comprises three tasks with the purpose of screeningTesting for disease in people without symptoms.
for cognitive impairment: clock drawing, abstraction, and 5-word recall (memory).
Scoring:
Each 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).
has different scoring and is interpreted independently.
DOC – Mood (total score 0-6)
The two items are scored from 0-3 whereby the respondent is asked to rate how often each symptom occurred over the last 2 weeks:
- 0 = not at all
- 1 = several days
- 2 = more than half of the days
- 3 = nearly every day.
DOC – Apnea (total score 0-4)
The four items are scored on a dichotomic scale (0 = no, 1 = yes) according to whether or not the respondent experiences each symptom.
DOC – Cog (total score 0-10)
- Clock drawing task (0-3 points): 1 point each is given for (i) contour, (ii) numbers and (iii) the hands of the clock.
- Abstraction task (0-2 points): 1 point is given for each item pair correctly answered.
- Delayed recall task (0-5 points): 1 point is given for each word recalled without any cues.
The score for each task is summed to calculate the 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.
Each 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).
is then summed to obtain a total score ranging between 0 and 20.
A raw score interpretation and a regression interpretation can be obtained at http://www.docscreen.ca/.
Time:
The DOC screen takes approximately 5 minutes to complete.
Subscales:
The DOC screen is comprised of three subscales: DOC Mood, DOC Apnea and DOC Cog.
Equipment:
A pencil and the test form are needed to complete the DOC screen.
Training:
No training requirements have been reported. The DOC screen can be administered by any individual who is able to correctly follow the instructions, but must be interpreted by a qualified health professional.
Alternative forms of the DOC Screen:
An alternative version is available and uses different words for the memory and abstraction tasks. This version must be used if the patient has previously been exposed to the MoCA or DOC screen to minimize any learning effects associated with repeated administration.
The E-DOC screen is an electronic version of the tool, which is available through the DOC screen website. The E-DOC screen has not been validated.
Client suitability
Can be used with:
- 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..
- The DOC screen may also be suitable for use among patients with other neurological and vascular disorders such as multiple sclerosis, Alzheimer’s disease, mild cognitive impairment, Parkinson’s Disease and traumatic brain injury. However, no study has been conducted with this population.
Should not be used with:
While no contraindications have been reported, some considerations must be made when completing the test:
- A translator, family member or caregiver can provide translation for patients who do not speak English fluently;
- Provide visual aid (e.g. glasses) for patients with visual loss;
- Speak loudly and clearly for patients with reduced hearing;
- Motor tasks such as the clock drawing activity may be difficult for patients with motor impairments – use sound clinical judgement for this task;
- Use alternative communication strategies 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).
In what languages is the measure available?
English
Summary
| What does the tool measure? |
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.
, obstructive sleep apnea and cognitive impairment 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.. |
| What types of clients can the tool be used for? |
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? |
ScreeningTesting for disease in people without symptoms.
. |
| Time to administer |
Five minutes. |
| Versions |
- DOC screen
- E-DOC screen
- A second version is available to minimize learning effects associated with repeated administration.
|
| Languages |
The DOC screen is only available in English. |
| 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.:
No studies have examined 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 DOC screen.
Test-retest:
No studies have examined 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 DOC screen.
Intra-rater:
No studies have examined intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater's subsequent ratings are contaminated by knowledge of earlier ratings.
of the DOC screen.
Inter-rater:
No studies have examined 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 DOC screen. |
ValidityThe degree to which an assessment measures what it is supposed to measure.
|
Criterion:
Concurrent:
No studies have examined concurrent validityTo validate a new measure, the results of the measure are compared to the results of the gold standard obtained at approximately the same point in time (concurrently), so they both reflect the same construct. This approach is useful in situations when a new or untested tool is potentially more efficient, easier to administer, more practical, or safer than another more established method and is being proposed as an alternative instrument. See also "gold standard."
of the DOC screen.
Predictive:
No studies have examined predictive validityA form of criterion validity that examines a measure's ability to predict some subsequent event. Example: can the Berg Balance Scale predict falls over the following 6 weeks? The criterion standard in this example would be whether the patient fell over the next 6 weeks.
of the DOC screen.
Construct:
Convergent/Discriminant:
No studies have examined convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
of the DOC screen.
Known groups:
No studies have examined known groups validityKnown groups validity is a form of construct validation in which the validity is determined by the degree to which an instrument can demonstate different scores for groups know to vary on the variables being measured.
. However, one study examined the 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."
and specificitySpecificity refers to the probability that a diagnostic technique will indicate a negative test result when the condition is absent (true negative).
and reported that the DOC screen is a valid measure that can reliably identify patients at high-risk of 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.
, obstructive sleep apnea and cognitive impairment. |
| Floor/Ceiling Effects |
No studies have examined the floor or ceiling effects of the DOC screen. |
| Does the tool detect change in patients? |
Not reported. |
| Acceptability |
The DOC screen is a standardized screeningTesting for disease in people without symptoms.
tool suitable for use 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. patients. |
| Feasibility |
The measure is brief, easy to score and requires no formal training. A study on 1503 patients showed that 89% of participants completed the screen in 5 minutes or less. |
| How to obtain the tool? |
The DOC screen is free to use for clinical and educational purposes.
The administration manual and forms are available online from the following website: http://www.docscreen.ca/
|
Psychometric Properties
Overview
We conducted a literature search to identify all relevant publications on the psychometric properties of the DOC screen in 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.. We identified only one study, which was published in part by the developers of the measure. More studies are required before definitive conclusions can be drawn regarding 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 .
and validityThe degree to which an assessment measures what it is supposed to measure.
of the DOC screen.
Floor/Ceiling Effects
No studies have examined the floor or ceiling effects of the DOC screen.
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.:
No studies have 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 DOC screen.
Test-retest:
No studies have 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 DOC screen.
Inter-rater:
No studies have 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 DOC screen.
Intra-rater:
No studies have examined the intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater's subsequent ratings are contaminated by knowledge of earlier ratings.
of the DOC screen.
Validity
Criterion:
Concurrent:
No studies have examined the concurrent validityTo validate a new measure, the results of the measure are compared to the results of the gold standard obtained at approximately the same point in time (concurrently), so they both reflect the same construct. This approach is useful in situations when a new or untested tool is potentially more efficient, easier to administer, more practical, or safer than another more established method and is being proposed as an alternative instrument. See also "gold standard."
of the DOC screen.
Predictive:
No studies have examined the predictive validityA form of criterion validity that examines a measure's ability to predict some subsequent event. Example: can the Berg Balance Scale predict falls over the following 6 weeks? The criterion standard in this example would be whether the patient fell over the next 6 weeks.
of the DOC screen.
Construct:
Convergent/Discriminant:
No studies have examined the convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
of the DOC screen.
Known groups:
No studies have examined the known groups validityKnown groups validity is a form of construct validation in which the validity is determined by the degree to which an instrument can demonstate different scores for groups know to vary on the variables being measured.
of the DOC screen.
Responsiveness
No studies have examined the responsivenessThe ability of an instrument to detect clinically important change over time.
of the DOC screen.
Sensitivity and Specificity:
Swartz et al. (2017) examined the 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."
and specificitySpecificity refers to the probability that a diagnostic technique will indicate a negative test result when the condition is absent (true negative).
of the DOC screen for detecting 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.
, obstructive sleep apnea and cognitive impairment using receiver operating characteristic (ROC), area under the curve analyses (AUC) and the two-cut point approach. DOC-Mood was compared with the Structured Clinical Interview for DSM Disorders (SCID-D) and excellent 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."
(92%) and specificity (99%) was identified for detecting 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.
(AUC=0.898). DOC-Apnea was compared with results on polysomnography (PSG) and excellent sensitivity (95%) and specificitySpecificity refers to the probability that a diagnostic technique will indicate a negative test result when the condition is absent (true negative).
(96%) for detecting obstructive sleep apnea was identified (AUC=0.660). DOC-Cog was compared to a 30-minute neuropsychological tests protocol proposed by Hachinski et al. (2006) and excellent 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."
(100%) and specificitySpecificity refers to the probability that a diagnostic technique will indicate a negative test result when the condition is absent (true negative).
(95%) for detecting cognitive impairment was identified (AUC=0.776).
References
- Hachinski, V., Iadecola, C., Petersen, R. C., Breteler, M. M., Nyenhuis, D. L., Black, S. E., … & Vinters, H. V. (2006). National Institute of Neurological Disorders and Stroke–Canadian stroke network vascular cognitive impairment harmonization standards. Stroke, 37 (9), 2220-2241.
- Swartz, R. H., Cayley, M. L., Lanctôt, K. L., Murray, B. J., Cohen, A., Thorpe, K. E., … & Herrmann, N. (2017). The “DOC” screen: Feasible and valid screening for depression, Obstructive Sleep Apnea (OSA) and cognitive impairment in stroke prevention clinics. PloS one, 12 (4), e0174451.
See the measure
How to obtain the DOC Screen?
The form and manual of administration are available online from the following website: http://www.docscreen.ca/
The Doc screen is free to use for clinical and educational purposes and therefore no permissions are required.
