[ENG]The PHQ-9 questionnaire is a screening test worldwide used to measure depression. But it cannot
be used in Costa Rica, due to the fact that it has not previously been validated for its population. The
present study aims to show the validation of the PHQ-9 questionnaire and its variants (PHQ-2, PHQ-
4, PHQ-8) in a population sample of adults residing in Costa Rica. A sample was collected (n = 1162)
using a self-administered questionnaire. Confirmatory Factor Analysis (CFA), Receiver Operating
Characteristic (ROC) curve, and Multiple Group Confirmatory Factor Analysis (MGCFA) were tested.
One factor was found that explained 73.33% of the variance with excellent internal consistency
(α = 0.928). Goodness-of-fit measures were adequate (RMSEA = 0.107; CFI = 0.948), as was diagnostic
power at a cut-off of 10 (78.60 for Sensitivity and 27.95 for 1-Specificity). External validation indices
were good (r = 0.843 with GAD-7, r = − 0.647 with RS14, and r = 0.301 with FCV19S), and the model
showed invariance by sex (Δχ2 = 27.90; df = 27; p < 0.001). Additionally, new cut-off points were
proposed for PHQ-9 and its variants for Costa Rican male, female, and general populations. The PHQ-9
and its variants (PHQ-2, 4, and 8) are valid tools for detecting depression (and anxiety for PHQ-4) in
Costa Rican population. In addition, new cut-off points differentiated by sex are proposed.
