Normative data and psychometric properties of the Patient Health Questionnaire-9 in a nationally representative Korean population

Abstract

Background: The Patient Health Questionnaire-9 (PHQ-9) has been standardized in several populations and is widely used in clinical practice and health care. However, it has not been appropriately standardized in the Korean general population, and no normative data have been presented. The aim of this study was to provide the normative data and psychometric properties of the PHQ-9 in the nationally representative population of Korea. Methods: We used the nationwide cross-sectional survey data of Korea from 2014 to 2016. The data of 10,759 individuals aged over 19 years were analyzed in this study. As the distribution of the PHQ-9 scores was not normative, the percentile ranks for raw scores were provided. The survey questionnaires included the PHQ-9, The EuroQol-5 Dimension (EQ-5D), and demographic characteristics. We analyzed the construct validity and internal consistency of the PHQ-9. Results: The normative data of the PHQ-9 were generated according to the sex and different age categories. The correlation coefficient between the sum of the PHQ-9 scores and the EQ-5D index was 0.44, which was moderate. The most appropriate model was the two-factor model with five 'affective-somatic' labeled items and four 'cognitive' labeled items. Cronbach's α for the PHQ-9 was 0.79. Conclusions: Our result supports reliability and validity with two-factor structure of PHQ-9 for measuring depression in the Korean nationally representative population. The Korean normative data on the PHQ-9 according to percentile rank can assist in interpreting and comparing scores with other populations.

Psychometric properties of the Norwegian version of the Patient Health Questionnaire-9 (PHQ-9) in a large female sample of adults with and without eating disorders

“…The internal consistency of the Norwegian version of the PHQ-9 was excellent among adult females, with Cronbach’s alphas between .86–.92 for the different ED groups. This is similar to results from the previous Norwegian adolescent study (Cronbach’s alpha of .86 for the total sample and .88 for girls only) [ 23 ], as well as other studies among adult (male and female) samples [ 17 , 45 ], all reporting Cronbach’s alphas between .79 and .89. Thus, reported internal consistency was similar across gender in these studies.…”

“…Normative data were also presented, demonstrating higher PHQ-9 mean scores in the ED groups compared to those with no lifetime ED. Though elevated scores may be expected among individuals with a previous ED, it is worth noting that the PHQ-9 mean score of the individuals with no ED history in our study is considerably higher than that reported among representative nationwide population-based samples from other studies, such as Germany [ 46 ], the USA [ 22 ], and South Korea [ 45 ]. Mean scores for males and females in these studies typically range from 2.5 to 4.5, though females tend to score somewhat higher than males.…”

“…211.188; p = 0.00; CFI = .95; TLI = .94; RMSEA = 0.095; [0.08–0.11]; SRMR = 0.107. Since the fit was mediocre, a two-factor solution proposed in the literature with cognitive and somatic symptoms was investigated [ 45 ]. The two-factor solutions gave somewhat better model-fit (χ 2 27 [ N = 762].…”

An Analysis of Suicide Risk Factors among Farmers in the Midwestern United States

“…The PHQ-9 [ 21 ] is a 9-item self-report measure that is widely used in health care settings to screen for depression in the general population [ 25 , 26 ]. The items in the PHQ-9 are calculated into a score with a range from 0 to 27.…”

Patterns of item score and total score distributions on depression rating scales in the general population: evidence and mechanisms

“…For inferential statistics, researchers often assume normality for such Likert type scale data. However, in the case of depression rating scales, a normal distribution is rarely observed in a general population [ 5 , 6 ]. As the majority of individuals in a general population have a few or no depressive symptoms, the item score and total score distributions on such a scale are usually skewed to the right [ 2 , 7 ].…”