title: Chronic condition comorbidity and multidrug therapy in general practice populations: a cross-sectional linkage study.
abstract: OBJECTIVE
  The study investigated (1) the association between comorbidity and multidrug prescribing compared with the index condition, and (2) the association between vascular comorbidity and non-vascular condition key drug prescribing.
  
  
  METHODS
  Cross-sectional study linking anonymised computer consultations with prescription records for a 2-year time period.
  
  
  METHODS
  11 general practices in North Staffordshire, England.
  
  
  METHODS
  Study groups aged 40 years and over (N=12 875). Within six conditions, comorbid group with the other five conditions was compared with an 'alone' group without them. Additionally, how the 'vascular' (one of diabetes, cardiovascular disease and cerebrovascular disease) comorbidity influenced chronic obstructive pulmonary disease (COPD), osteoarthritis (OA) or depression drug prescribing was investigated.
  
  
  METHODS
  Based on the British National Formulary, five main drug chapters constituted a measure of drug counts, with low count as 2 or less and high multidrug count as 3 or more. Key drugs prescribed for COPD, OA and depression were derived from guidelines.
  
  
  RESULTS
  The adjusted associations between the comorbid groups and higher multidrug count compared with their respective 'alone' group were: odds ratio (OR) 7.1 (95% CI 5.6 to 9.0) for depression, OR 5.4 (95% CI 4.6 to 6.3) for cardiovascular disease, OR 3.7 (95% CI 2.8 to 5.0) for cerebrovascular disease, OR 3.6 (95% CI 3.1 to 4.3) for OA, OR 3.5 (95% CI 3.0 to 4.2) for diabetes and OR 3.2 (95% CI 2.6 to 4.0) for COPD. In COPD, vascular comorbidity was associated with a significant reduction in key COPD drug treatments (adjusted OR 0.6 (95% CI 0.4 to 0.8). In depression, vascular comorbidity was associated with a reduction in key depression drug treatments (OR 0.6 (95% CI 0.4 to 0.7)).
  
  
  CONCLUSIONS
  Our findings show that multidrug prescribing for different body systems is higher with comorbidity and may be associated with lower likelihood of prescribing for specific conditions. Further research is required on whether multidrug prescribing influences the outcomes of care for chronic conditions.
authors.affiliation: Department of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Eyitope R
authors.initials: ER
authors.lastname: Roberts
authors.affiliation: Arthritis Research UK Primary Care Centre, Keele University, Newcastle-under-Lyme, Staffordshire, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Green
authors.affiliation: Health Services Research Unit, Keele University, Newcastle-under-Lyme, Staffordshire, UK.
authors.forename: Umesh T
authors.initials: UT
authors.lastname: Kadam
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D003863:Depression / Q000150:complications* / Q000188:drug therapy*; D005260:Female; D058006:General Practice; D006801:Humans; D008297:Male; D008498:Medical Record Linkage; D008875:Middle Aged; D010003:Osteoarthritis / Q000150:complications* / Q000188:drug therapy*; D019338:Polypharmacy; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000188:drug therapy*; D014652:Vascular Diseases / Q000150:complications* / Q000188:drug therapy*
keywords: CARDIOLOGY; EPIDEMIOLOGY; MENTAL HEALTH; RESPIRATORY MEDICINE (see Thoracic Medicine); RHEUMATOLOGY; THERAPEUTICS