Validation of the PHQ-9 in a psychiatric sample

BACKGROUND

The PHQ-9 was originally developed as a screener for depression in primary care and is commonly used in medical settings. However, surprisingly little is known about its psychometric properties and utility as a severity measure in psychiatric populations. We examined the full range of psychometric properties of the PHQ-9 in patients with a range of psychiatric disorders (i.e., mood, anxiety, personality, psychotic).

METHODS

Patients (n=1023) completed the PHQ-9 upon admission and discharge from a partial hospital, as well as other self-report measures of depression, anxiety, well-being, and a structured diagnostic interview.

RESULTS

Internal consistency was good (α=.87). The PHQ-9 demonstrated a strong correlation with a well-established measure of depression, moderate correlations with related constructs, a weak correlation with a theoretically unrelated construct (i.e., disgust sensitivity), and good sensitivity to change, with a large pre- to post-treatment effect size. Using a cut-off of ≥13, the PHQ-9 demonstrated good sensitivity (.83) and specificity (.72). A split-half exploratory factor analysis/confirmatory factor analysis suggested a two-factor solution with one factor capturing cognitive and affective symptoms and a second factor reflecting somatic symptoms. Psychometric properties did not differ between male and female participants.

LIMITATIONS

No clinician-rated measure of improvement, and the sample lacked ethnoracial diversity.

CONCLUSIONS

This first comprehensive validation of the PHQ-9 in a large, psychiatric sample supported its use as a severity measure and as a measure of treatment outcome. It also performed well as a screener for a current depressive episode using a higher cut-off than previously recommended for primary care samples.

Abnormal error processing in depressive states: a translational examination in humans and rats

Depression has been associated with poor performance following errors, but the clinical implications, response to treatment and neurobiological mechanisms of this post-error behavioral adjustment abnormality remain unclear. To fill this gap in knowledge, we tested depressed patients in a partial hospital setting before and after treatment (cognitive behavior therapy combined with medication) using a flanker task. To evaluate the translational relevance of this metric in rodents, we performed a secondary analysis on existing data from rats tested in the 5-choice serial reaction time task after treatment with corticotropin-releasing factor (CRF), a stress peptide that produces depressive-like signs in rodent models relevant to depression. In addition, to examine the effect of treatment on post-error behavior in rodents, we examined a second cohort of rodents treated with JDTic, a kappa-opioid receptor antagonist that produces antidepressant-like effects in laboratory animals. In depressed patients, baseline post-error accuracy was lower than post-correct accuracy, and, as expected, post-error accuracy improved with treatment. Moreover, baseline post-error accuracy predicted attentional control and rumination (but not depressive symptoms) after treatment. In rats, CRF significantly degraded post-error accuracy, but not post-correct accuracy, and this effect was attenuated by JDTic. Our findings demonstrate deficits in post-error accuracy in depressed patients, as well as a rodent model relevant to depression. These deficits respond to intervention in both species. Although post-error behavior predicted treatment-related changes in attentional control and rumination, a relationship to depressive symptoms remains to be demonstrated.

Beyond generalized anxiety disorder: psychometric properties of the GAD-7 in a heterogeneous psychiatric sample

BACKGROUND

Although developed as a screener for Generalized Anxiety Disorder (GAD) in primary care, the GAD-7 is now commonly used as a measure of general anxiety symptoms across various settings and populations. However, little is known about its psychometric properties when used in such heterogeneous samples. We examined the internal consistency, convergent validity, sensitivity and specificity, sensitivity to change, and structure of the GAD-7 in patients receiving brief, intensive CBT treatment in a partial hospital setting. We also examined the properties of a modified version that assessed symptoms over the past 24-h.

METHODS

Participants (n=1082) completed the GAD-7 upon admission and discharge from a partial hospital program. They also completed measures of worry, depression, and well being and a structured diagnostic interview. We examined psychometric properties in the total sample and separately for patients with GAD, post-traumatic stress disorder, Social Anxiety Disorder (SAD), and panic disorder.

RESULTS

Internal consistency and convergent validity were good for the total sample and each anxiety disorder group. The GAD-7 demonstrated poor specificity and a high false positive rate for all anxiety disorders. Sensitivity to change was generally good. Factor analysis revealed that a one-factor structure did not fit the data well. The 24-h version performed similarly to the original version.

CONCLUSIONS

The GAD-7 performed well as a measure of anxiety symptom severity, but not as a screener in this psychiatric sample. It is a useful outcome measure for hetereogenous samples, but it may not perform as well specifically for individuals with SAD. A modified version of the GAD-7 that assessed anxiety symptoms over the past 24-h appears to be a reliable and valid modification.

Effects of public posting on driving speed in Icelandic traffic

We replicated a study by Van Houten, Nau, and Marini (1980) that had revealed reductions in vehicle speeding following the posting of percentages of drivers not speeding on a sign at roadside. Our subjects were drivers entering a residential area where the speed limit changed from 90 km/hr (55.9 mph) to 60 km/hr (37.3 mph). A total of 4,409 vehicle speeds were taken from two observation sessions per day for 20 consecutive weekdays. The intervention consisted of a single posting condition, in which a hypothetical daily percentage of drivers not speeding was posted on a feedback sign, followed by a double posting condition, in which a sign posting a best result was erected beyond the feedback sign. Results revealed a significant speed reduction from an average of 69.0 km/hr (42.9 mph) during baseline to 63.4 km/hr (39.4 mph) during single posting. Average speed during double posting was 62.9 km/hr (39.1 mph). The percentage of drivers exceeding 70 km/hr (43.5 mph) dropped from 41.0 during baseline to 20.5 during single posting. The significant speed reductions add to the generality of findings of similar studies in Canada and Israel and offer possible explanations for the failure of feedback posting to reduce speed in the U.S.

Evaluation of an Icelandic translation of the Basic Personality Inventory using a bilingual sample

This study investigated the similarity of Icelandic and English versions of the Basic Personality Inventory (BPI), a 240-item measure of psychopathology. Eighty-nine native Icelandic graduate students studying in North America completed both language versions of the BPI in a counterbalanced order with a retest interval of approximately one month. The results of this bilingual retest study confirmed the adequacy of the Icelandic translation. Specifically, scale means, test-retest coefficients, and reliability coefficients demonstrated that the BPI performed highly similarly in both language versions. These findings provide additional support for the adequacy and applicability of the Icelandic translation of the BPI.