[Reliability and dimensionality of PHQ-9 in screening depression symptoms among health science students in Cartagena, 2014].

INTRODUCTION: Depression among university students must be screened with valid instruments. The Patient Health Questionnaire (PHQ-9) is reliable and valid for screening depression in a university context; however, its psychometric performance in Colombia is unknown. OBJECTIVE: To estimate the reliability and dimensionality of PHQ-9 as a screening instrument for depressive symptoms among health sciences students of a university in Cartagena, Colombia.Materials y methods: We analyzed the factorial structure and reliability of the PHQ-9 in a sample of 550 students for expected prevalence of clinically-meaningful depressive symptoms (CMDS) of 25% with a confidence level of 95% and an error level of 3%. We used the free Spanish version of PHQ-9 for Colombia, authorized by its creators. A confirmatory factorial analysis, and an estimate of internal consistency using Cronbach´s alfa and McDonald´s omega were obtained. RESULTS: We analyzed 541 surveys. The average age of the group was 20.18 (SD=2.59) years old, 354 (63.77%) participants were women and 196 (36.23%) men. CMDS prevalence was 27.3%. The confirmatory factorial analysis exhibited a two-factor model, which explained the total variance of 42.80%. The proportion of variance explained by the factors was 0.243 (item 5) and 0.587 (item 2). Cronbach´s alfa was 0.830 and McDonald´s omega, 0.89. CONCLUSIONS: PHQ-9 was a valid and reliable tool for screening depressive symptoms among health sciences students in a university in Cartagena, Colombia.