Differences in Adult PHQ9 Administration at KP Northwest by Demographic and Census Factors

Background: The Patient Health Questionnaire (PHQ-9) is a depression screener that scores each of the nine DSM-IV depression criteria from the original PRIME-MD. With the increased administration and electronic capture of data from the PHQ-9 instrument, it has added research value to its existing usefulness as a clinical evaluation tool. Recent inclusion in Health Care Systems Research Network’s virtual data warehouse (VDW) means that researchers can look at PHQ-9 data in the context of other important patient health and demographic factors. Methods: We interrogated the Kaiser Permanente Northwest (KPNW) VDW for demographic, diagnosis, enrollment, and PHQ-9 and U.S. Census data for the years 2014–2015. Age, gender and race/ethnicity were combined with Census education and income, PHQ-9 dates and ICD-9/10 depression diagnoses. Within the sampling frame of all adults aged 18–90 years with any KPNW enrollment in 2014 and 2015, we compared four groups: among patients with a PHQ-9 screening over the study years, those (a) with, and (b) without one or more clinical depression diagnoses; and among patients without a PHQ-9 screening, those (c) with, and (d) without one or more depression diagnoses. Results: Patients completing the PHQ-9 differed in several ways from adults who did not complete the PHQ-9. The PHQ-9 group was older (mean age: 49.7 vs 45.9 years) and more often female (64.6% vs 49.4%) and non-Hispanic white (82.1% vs 66.7%). A notably lower percentage of PHQ-9 screened patients were non-Hispanic Asian (2.4% vs 4.7% with no screening). As expected, the PHQ-9 group was demographically similar to the group with the depression diagnoses, with some minor differences on gender. Patients with a depression diagnosis and a PHQ-9 administration were slightly more often female compared to those without a PHQ-9 (69.9% vs 66.9%). Census comparisons indicate that patients with a depression diagnosis and a PHQ-9 lived in areas with slightly lower educational attainment versus patients with a depression diagnosis only (28% of adults in their Census area had a bachelor’s degree vs 31% without, respectively). No differences were observed on income. Conclusion: The PHQ-9 is differentially administered among adult patients at KPNW. But the administration does follow the demographic spectrum of depression