Improving the Measurement Properties of Depressive Symptom Instruments for Use after SCI

Transcription

1 Improving the Measurement Properties of Depressive Symptom Instruments for Use after SCI Allen Heinemann, PhD Ryan Williams, PhD Charles Bombardier, PhD Martin Forchheimer, MPP Jesse Fann, MD Holly Neumann, MPPA Northwestern University/Rehabilitation Institute of Chicago University of Washington University of Michigan

2 Background Mood disorders occur frequently after SCI Routine assessment of depressive symptoms is challenging, in part because instruments are not tailored to this population 2

3 Hamilton Rating Scale for Depression Interviewer administered Long regarded as the gold standard in assessing depression symptom severity Used with medical rehabilitation populations including stroke, Parkinson s disease, and SCI 7-item version demonstrates good test-retest reliability after the development of a structured interview guide Demonstrates good internal consistency and acceptable sensitivity and specificity as a depression screener 3

4 Patient Health Questionnaire-9 Patient-reported outcome instrument Assesses depression symptom severity Developed for use in clinical settings as a brief, patient-reported alternative to clinician diagnostic questionnaires Utilized in health and outcomes research including the SCI and Traumatic Brain Injury Model Systems 4

5 Symptom Checklist-20 Patient-reported outcome instrument for symptoms of psychopathology Contains a 20-item depression subscale Revised SCL-20 demonstrates high reliability, construct and convergent validity Low discriminant validity, limiting its use to screening Factor structure suggests it is a measure of general distress Used in more than 2,000 clinical trials due to its high sensitivity 5

6 Objective To compare the measurement properties of three depression screeners To tailor the instruments for depression screening of adults with SCI 6

7 Methods Data drawn from a randomized controlled trial of venlafaxine XR for major depressive disorder Subjects completed the PHQ-9 and SCL-20 when screened for eligibility Interviewers completed the HAM-D concurrently MDD was diagnosed independently 7

8 Analytic Plan Rating scale (Rasch) analysis Pearson correlation analysis of revised measures Growth curve analysis of treatment vs. control groups 8

9 Sample Characteristics 2,536 people screened 133 randomized to treatment 126 retained at 12 weeks Demographic characteristics Mean age: 40 years Male gender: 74% male Injury characteristics Cervical injury: 47% Complete lesion: 53% (ASIA A) 9

10 Result Highlights All instruments demonstrated rating scale problems Combining rating scale categories improved internal consistency Person separation reliability >.75 Items mistargeted to sample (relatively low rate of depressive symptoms) Some items misfit the underlying construct Correlations among the instruments were high (>.70) Correlations with MDD diagnosis were high (>.79) 10

11 Measurement Properties of the PHQ-9, SCL-20, and HAM-D PHQ-9 SCL-20 HAM-D Original Revised Original Revised Original Revised Number of Items Number of Observations Scale Categories Varies Varies Person Separation Cronbach s α N Misfitting Items Item-Measure Corr Variance Explained 51.8% 48.4% 46.9% 45.3% 43.2% 46.6% by Measures (Eigenvalue) (9.7) (8.4) (17.7) (11.6) (12.9) (9.6) Residual Variance Explained by 1 st Contrast 9.8% (1.8) 10.4% (1.8) 8.0% (3.0) 9.5% (2.4) 6.4% (1.9) 8.3% (1.7) Percent at Floor 5.1% 5.1% 2.9% 9.7% 2.4% 3.6%

12 Correlations among depressive symptom measures and MDD diagnosis diagnosis PHQ-9 SCL-20 HAM-D Maier Bech PGI CGI SCL HAM-D Maier Bech PGI CGI SCID-D

13 Treatment-Control Standardized Mean Differences (95% CI)

14 Depression Measure Growth Profiles

15 Conclusions The SCL-20 and HAM-D contained items that misfit the underlying construct and that correlated weakly with the total measure Removing misfitting items improved the internal consistency of the derived measures and reduced respondent burden Psychometric properties of the PHQ-9 were as good as or better than the SCL-20 and the HAM-D PHQ-9 is ideal for clinical and research applications Simplest instrument to administer Requires few modifications Demonstrates excellent reliability and correspondence with MDD diagnosis 15

16 Study Limitations Sample may not be representative of all persons with SCI who develop depressive symptoms Respondents were served by larger rehabilitation hospitals with the capacity to provide high quality services Participants were willing to undergo random assignment to treatment or control conditions after discontinuing antidepressant medications 16

17 Clinical Implications Psychometric properties of the 3 revised depression instruments are more than adequate for routine use in adults with SCI The PHQ-9 is the simplest instrument to administer and demonstrates psychometric properties that are as good or better than the 2 other instruments Derived measures are sufficiently sensitive to detect clinical improvement over the course of a 12-week treatment trial 17

18 Acknowledgments National Institute on Disability and Rehabilitation Research H133A