The measurement invariance of the Patient Health Questionnaire-9 for American Indian adults

Background: American Indian people have high suicide rates. However, little epidemiological data is available on depression prevalence, a suicide risk factor, in this population. Some research suggests that depression scales may perform differently for American Indian people. However, the Patient Health Questionnnaire-9 (PHQ-9), a depression scale widely-used in clinical practice, had not been assessed for cross-cultural measurement invariance with American Indian people. Methods: In this retrospective study of existing electronic health record (EHR) data in an upper Midwestern healthcare system, we assessed the measurement invariance of the standard one-factor PHQ-9 and five previously identified two-factor models for 4443 American Indian and 4443 Caucasian American adults (age > = 18) with a PHQ-9 in the EHR from 12/1/2005 to 12/31/2017. We also conducted subgroup analyses with adults ages > = 65. Results: Models showed good fits (e.g., CFI > 0.99, RMSEA < 0.05) and internal consistency reliability (ordinal alpha > 0.80). All models displayed measurement invariance between racial groups. Factor correlation was high for two-factor models, providing support for the one-factor model. American Indian adults had significantly higher odds of PHQ-9 total scores > = 10 and > = 15 than Caucasian American adults. Limitations: Data came from a single healthcare system. Conclusions: The PHQ-9 exhibited cross-cultural measurement invariance between American Indian and Caucasian American adults, supporting the PHQ-9 as a depression screening tool in this clinical care population. American Indian adults also had higher levels of depression than Caucasian Americans. Future research could confirm the generalizability of our findings to other American Indian populations.