title: Associations between cardiovascular disease severity, osteoarthritis co-morbidity and physical health: a population-based study.
abstract: OBJECTIVE
  The aim of this study was to investigate the interaction between cardiovascular disease severity and OA co-morbidity on physical health.
  
  
  METHODS
  A baseline questionnaire was mailed to 9676 patients aged ≥40 years from UK family practices. A priori exclusive morbidity groups were constructed as follows, based on records 3 years before baseline: (i) reference group--neither cardiovascular disease nor OA; (ii) cardiovascular disease severity index groups--with hypertension, ischaemic heart disease or heart failure without OA; (iii) OA index group without cardiovascular disease and (iv) co-morbid severity groups with hypertension, ischaemic heart disease or heart failure with OA. Adjusted associations between morbidity groups and physical health [mean physical component summary (PCS) score based on the 12-item Short Form Health Survey (SF-12)] compared with the reference group were assessed using linear regression methods.
  
  
  RESULTS
  A total of 5426 patients responded to the baseline questionnaire (56% response). The adjusted mean difference in PCS score between the reference group and the cardiovascular disease index were -2.4 (95% CI -3.4, -1.4) for hypertension, -5.3 (-6.3, -4.3) for ischaemic heart disease and -11.8 (-13.6, -9.9) for heart failure. The difference in the score for the index OA group was -5.6 (-6.5, -4.6). Estimates for co-morbid OA groups were -6.8 (-7.9, -5.7) for hypertension, -9.1 (-10.6, -7.6) for ischaemic heart disease and -12.8 (-16.0, -9.7) for heart failure.
  
  
  CONCLUSIONS
  In cardiovascular populations with differing severity, the co-morbid addition of OA was associated with incrementally poorer physical health, but such interactions were less than additive.
authors.affiliation: Research Institute for Primary Care and Health Sciences and Health Services Research Unit, Keele University, Keele, UK. j.a.prior@keele.ac.uk.
authors.forename: James A
authors.initials: JA
authors.lastname: Prior
authors.affiliation: Research Institute for Primary Care and Health Sciences and Health Services Research Unit, Keele University, Keele, UK.
authors.forename: Kelvin P
authors.initials: KP
authors.lastname: Jordan
authors.affiliation: Research Institute for Primary Care and Health Sciences and Health Services Research Unit, Keele University, Keele, UK. Research Institute for Primary Care and Health Sciences and Health Services Research Unit, Keele University, Keele, UK.
authors.forename: Umesh T
authors.initials: UT
authors.lastname: Kadam
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000453:epidemiology*; D015897:Comorbidity; D005260:Female; D006304:Health Status; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000453:epidemiology*; D011788:Quality of Life; D012720:Severity of Illness Index
keywords: cardiovascular diseases; chronic disease; co-morbidity; cohort studies; osteoarthritis