Case-mix adjustments for patient reported experience and outcome measures in primary care: an empirical approach to identify patient characteristics as case-mix adjusters based on a secondary analysis of an international survey among patients and their general practitioners in 34 countries

Journal of Patient-Reported Outcomes

Box 1 Variables from the literature about case-mix adjustment in PREMs in primary care

Johnson et al., 2010 [25]:	lll
Outcome variable: PREMs from CAHPS
Case-mix adjusters: self-reported health, age, education, race/ethnicity, usual language spoken
Damman et al., 2011 [11]:
Outcome variable: PREMs from Consumer Quality index General Practice
Case-mix adjusters: age, general health status, mental health status, education, sex, and ethnicity
Paddison et al., 2012 [7]:
Outcome variable: PREMs in three domains of primary care: access; interpersonal care; anticipatory care planning, and overall satisfaction with primary care services
Case-mix adjusters: age, sex, ethnicity, self-reported health, and socio-economic status of residential address
Hatfield and Zaslavsky (2017) [13]:
Outcome variable: PREMs of process quality from CAHPS
Case-mix adjusters: self-reported general health status, mental health status, education level