How to compare scores from different depression scales: equating the Patient Health Questionnaire (PHQ) and the ICD-10-Symptom Rating (ISR) using Item Response Theory.

Publisher: John Wiley & Sons Country of Publication: United States NLM ID: 9111433 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1557-0657 (Electronic) Linking ISSN: 10498931 NLM ISO Abbreviation: Int J Methods Psychiatr Res Subsets: MEDLINE

Publication: Hoboken, NJ : John Wiley & Sons
Original Publication: Chichester ; New York : Wiley, c1991-

International Classification of Diseases* ; Psychiatric Status Rating Scales* ; Surveys and Questionnaires*; Depression/*diagnosis; Adolescent ; Adult ; Aged ; Aged, 80 and over ; Depression/psychology ; Female ; Humans ; Male ; Middle Aged ; Models, Anatomic ; Psychometrics/methods ; Reproducibility of Results ; Weights and Measures ; Young Adult

A wide range of questionnaires for measuring depression are available. Item Response Theory models can help to evaluate the questionnaires exceeding the boundaries of Classical Test Theory and provide an opportunity to equate the questionnaires. In this study after checking for unidimensionality, a General Partial Credit Model was applied to data from two different depression scales [Patient Health Questionnaire (PHQ-9) and ICD-10-Symptom Rating (ISR)] obtained in clinical settings from a consecutive sample, including 4517 observations from a total of 2999 inpatients and outpatients of a psychosomatic clinic. The precision of each questionnaire was compared and the model was used to transform scores based on the assumed underlying latent trait. Both instruments were constructed to measure the same construct and their estimates of depression severity are highly correlated. Our analysis showed that the predicted scores provided by the conversion tables are similar to the observed scores in a validation sample. The PHQ-9 and ISR depression scales measure depression severity across a broad range with similar precision. While the PHQ-9 shows advantages in measuring low or high depression severity, the ISR is more parsimonious and also suitable for clinical purposes. Furthermore, the equation tables derived in this study enhance the comparability of studies using either one of the instruments, but due to substantial statistical spread the comparison of individual scores is imprecise.
(Copyright © 2011 John Wiley & Sons, Ltd.)

JAMA. 1999 Nov 10;282(18):1737-44. (PMID: 10568646)
J Affect Disord. 2004 Jul;81(1):61-6. (PMID: 15183601)
Qual Life Res. 2007;16 Suppl 1:5-18. (PMID: 17375372)
Qual Life Res. 2000 Mar;9(2):185-93. (PMID: 10983482)
Z Psychosom Med Psychother. 2008;54(4):409-18. (PMID: 19049690)
Annu Rev Clin Psychol. 2009;5:27-48. (PMID: 18976138)
Int J Methods Psychiatr Res. 2009;18(1):23-36. (PMID: 19194856)
Qual Life Res. 2003 Dec;12(8):981-1002. (PMID: 14651417)
Psychother Psychosom Med Psychol. 2010 Aug;60(8):307-15. (PMID: 19399700)
J Gen Intern Med. 2001 Sep;16(9):606-13. (PMID: 11556941)
J Pers Assess. 1985 Dec;49(6):571-8. (PMID: 4093836)
Psychother Psychosom Med Psychol. 2011 Mar;61(3-4):162-9. (PMID: 20401827)
Qual Life Res. 2005 Dec;14(10):2277-91. (PMID: 16328907)
Eur J Cancer. 2006 Dec;42(18):3169-77. (PMID: 17045472)
J Psychosom Res. 2005 Feb;58(2):163-71. (PMID: 15820844)
Psychother Psychosom. 2004 Nov-Dec;73(6):386-90. (PMID: 15479995)
Qual Life Res. 2003 Dec;12(8):913-33. (PMID: 14651412)
Med Care. 2004 Dec;42(12):1194-201. (PMID: 15550799)

Date Created: 20111025 Date Completed: 20120330 Latest Revision: 20211020

20240829

PMC6878401

10.1002/mpr.350

22021205