title: Concordance between the PHQ-9 and the HSCL-20 in depressed primary care patients.
abstract: BACKGROUND
  Two instruments commonly used in primary care research to measure depressive severity are the Patient Health Questionnaire-9 (PHQ-9) and the Hopkins Symptom Checklist-20 (HSCL-20). However, there is little information regarding the relationship between clinical information derived from these scales. The present study investigates the psychometric properties of the PHQ-9 and HSCL-20, determines the degree of instrument concordance, and describes the factor structure of the HSCL-20.
  
  
  METHODS
  A secondary data analysis from a randomized controlled trial was performed. A total of 405 primary care patients with major depressive disorder and/or dysthymia were administered the PHQ-9 and the HSCL-20 when recruited for the study.
  
  
  RESULTS
  Good internal consistency reliability estimates were obtained for both scales (PHQ-9 alpha=0.803; HSCL-20 alpha=0.837). All PHQ-9 inter-item and corrected item-total correlations showed that no item detracted from overall scale functioning. HSCL-20 items assessing overeating, poor appetite, and sexual interest were poorly correlated with other items and with the total scale score. A positive, moderate strength relationship was found between the instruments (r=0.54, p<0.0001). Exploratory factor analysis of the HSCL-20 yielded a six-factor structure, which accounted for almost 63% of the variance in total score. The largest contribution to common variance in the scale was provided by an "anxiety and self-reproach" factor.
  
  
  CONCLUSIONS
  PHQ-9 and HSCL-20 total scores were moderately correlated. Although the HSCL-20 is utilized as a measure of depression severity, it may lack sufficient specificity to be an accurate reflection of depression status per se.
authors.affiliation: Dartmouth Medical School, 7925 Rubin Building, 8th Floor, One Medical Center Drive, Lebanon, NH 03756-0001, United States. pamela.w.lee@dartmouth.edu
authors.forename: Pamela W
authors.initials: PW
authors.lastname: Lee
authors.forename: Herbert C
authors.initials: HC
authors.lastname: Schulberg
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Raue
authors.forename: Kurt
authors.initials: K
authors.lastname: Kroenke
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001007:Anxiety / Q000175:diagnosis / Q000523:psychology; D003866:Depressive Disorder / Q000175:diagnosis* / Q000523:psychology; D005260:Female; D006167:Guilt; D006801:Humans; D008297:Male; D010555:Personality Inventory / Q000706:statistics & numerical data*; D011320:Primary Health Care; D011594:Psychometrics / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D013223:Statistics as Topic; D014481:United States