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Objective We examine the reliability and validity of the Patient Health Questionnaire Anxiety-Depression Scale (PHQ-ADS) – which combines the PHQ-9 and GAD-7 scales – as a composite measure of depression and anxiety. Methods Baseline data from 896 patients enrolled in 2 primary-care based trials of chronic pain and 1 oncology-practice based trial of depression and pain were analyzed. The internal reliability, standard error of measurement (SEM), and convergent, construct, and factor structure validity, as well as sensitivity to change of the PHQ-ADS were examined. Results The PHQ-ADS demonstrated high internal reliability (Cronbach's alpha of 0.8 to 0.9) in all 3 trials. PHQ-ADS scores can range from 0 to 48 (with higher scores indicating more severe depression/anxiety), and the estimated SEM was approximately 3 to 4 points. The PHQ-ADS showed strong convergent (most correlations 0.7-0.8 range) and construct (most correlations 0.4-0.6 range) validity when examining its association with other mental health, quality of life and disability measures. PHQ-ADS cutpoints of 10, 20, and 30 indicated mild, moderate, and severe levels of depression/anxiety, respectively. Bi-factor analysis showed sufficient unidimensionality of the PHQ-ADS score. PHQ-ADS change scores at 3 months differentiated (P < .0001) between individuals classified as worse, stable, or improved by a reference measure, providing preliminary evidence for sensitivity to change. Conclusions The PHQ-ADS may be a reliable and valid composite measure of depression and anxiety which, if validated in other populations, could be useful as a single measure for jointly assessing two of the most common psychological conditions in clinical practice and research. Trial Registration clinicaltrials.gov Identifier: NCT00926588 (SCOPE); NCT00386243 (ESCAPE); NCT00313573 (INCPAD);

Minimally important difference (MID) refers to the smallest meaningful difference that carries implications for patient care. Minimally important differences are necessary to help interpret patient-reported pain outcomes in research and clinical practice. The PROMIS pain interference scales were validated across diverse samples; however, more information about their MIDs could improve their interpretability. The purpose of this study was to estimate MIDs for 4 fixed-length PROMIS pain interference scales, including the 6-item Pain Short Form and the 4-, 6-, and 8-item pain interference scales used in the PROMIS profile instruments. Data were analyzed from 3 randomized controlled trials (N = 759). The 3 samples, respectively, consisted of patients with chronic low back pain (n = 261), chronic back pain or hip/knee osteoarthritis pain (n = 240), and a history of stroke (n = 258). For each sample, anchor- and distribution-based approaches were used to estimate MIDs. Standard error of measurement and effect sizes were used as distribution-based MID estimates. Anchor-based MID estimates were established by mapping PROMIS pain interference scores onto established anchor measures, including the Brief Pain Inventory, and retrospective and prospective global ratings of change. The distribution- and anchor-based MID estimates showed convergence. For the pain samples, MID estimates ranged from 2 to 3 T-score points. For the nonpain sample, MID estimates ranged from 3.5 to 4.5 T-score points. The MID estimates were comparable across the 4 fixed-length scales. These MIDs can be used to evaluate treatment effects in research and clinical care and to calculate estimates for powering clinical trials.

The PROMIS four-item depression and anxiety scales are reasonable options as ultra-brief measures for screening in patients with chronic pain.