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Self-report depression screening instruments can save provider time, minimize stigma, engage patients in the identification of their symptoms of depression, and improve care coordination through routine tracking of patients. Screening instruments can be powerful tools in assisting primary care providers with detecting depression in their patient population, diagnosing depression and monitoring treatment response. These instruments can also help track a patient’s overall depression severity as well as the specific symptoms that are improving or not with treatment. Accurate screening, diagnosis and treatment of depression are entirely dependent on accurate measurement of symptoms in mental health. Inaccurate assessment in primary care is an independent predictor of poor control of chronic disease and is a significant contributor to health disparities, lack of patient satisfaction and poor-quality patient education and understanding of their disorder.
Methods
Baseline data were from two federally funded research studies testing a novel intervention the treatment of depression among Hispanics in primary care. Depression screening and related assessment were completed at baseline prior to a patient education session. Across all samples, 500 participants provided responses to the PHQ9 during pre-intervention screening. Confirmatory factor analyses (CFA) using full-information maximum likelihood estimation in Mplus 8.0. Modifications to the model were included where correlation of error terms would generate a model 𝜒2 difference greater than 9.0. Additional analyses included tests of reliability and psychometric validity and were performed in SPSS 25.0.
Results
PHQ-9 item scores corelated significantly with scale total scores, ranging from .422 to .596, all p<.001. Initial CFA analyses indicated moderate fit of the model (𝜒2 [27, N=500] =87.658, p<.001; 𝜒2/df=3.24; CFI=.872; TLI=.830; RMSEA=.067 [90% CI: .052, .106]; SRMR=.074). Four correlated error terms were added to the model resulting in excellent model fit for the PHQ-9 (𝜒2 [23, N=500] =34.448, p=.06; 𝜒2/df=1.50; CFI=.976; TLI=.962; RMSEA=.032 [90% CI: .000, .052]; SRMR=.028). Standardized factor loadings ranged from .259 to .634, all p<.001. Internal consistency reliability remained poor (𝛼=.679). Discriminant item functioning testing through corrected item-total correlations indicated good to excellent discrimination among all items (r ranged from .232 to .425). PHQ-9 scores were significantly correlated with GAD-7 anxiety scores, r=.558, p<.001. Women in the sample reported significantly greater PHQ-9 scores (M=17.03, SD=4.12) than men (M=15.10, SD=3.39, t=2.89, df=497, p=.004, Cohen d= 0.48). PHQ-9 scores did not significantly differ by marital status (F=.640, p=.634) or educational level (F=1.041, p=.393).
Conclusion
Results indicate modest support for the PHQ-9 and its use among Hispanics in primary care settings for the purpose of depression screening. Findings further support existing knowledge about the correlation between depression and anxiety. Since the PHQ-9 is the mostly wide used depression screening measure in primary care, inadequate evaluation of symptoms could lead to significant under identification of the disorder and contribute to mental health disparities in Hispanics. More research is needed on accurate depression symptom detection in different populations.