Interformat reliability of the patient health questionnaire: Validation of the computerized version of the PHQ-9

Computerized versions of well-established measurements such as the PHQ-9 are widely used, but data on the comparability of psychometric properties are scarce.

Our objective was to compare the interformat reliability of the paper-and-pen version with a computerized version of the PHQ-9 in a clinical sample.

130 participants with mental health disorders were recruited during psychotherapeutic treatment in a mental health clinic. In a crossover design, they all completed the PHQ-9 in both the computerized and paper-and-pen versions in randomized order.

The internal consistency was comparable for the computer (α = 0.88) and paper versions (α = 0.89), and highly significant correlations were found between the formats (r = 0.92). PHQ-9 total scores were not significantly different between the paper and the computer delivered versions. There was a significant interaction effect between format and order of administration for the PHQ-9, indicating that the first administration delivered slightly higher scores.

In order to reduce the required effort for the participants, we did not ask them to fill out anything but the PHQ-9 once in paper and once in computer version.

Our findings suggest that the PHQ-9 can be transferred to computerized use without affecting psychometric properties in a clinically meaningful way.