The effect of specialist care within the first year on subsequent outcomes in 24,232 adults with new-onset diabetes mellitus: population-based cohort study

F A McAlister, S R Majumdar, D T Eurich, J A Johnson, F A McAlister, S R Majumdar, D T Eurich, J A Johnson

Abstract

Background: Although specialty care has been shown to improve short-term outcomes in patients hospitalised with acute medical conditions, its effect on patients with chronic conditions treated in the ambulatory care setting is less clear.

Objective: To examine whether specialty care (ie, consultative care provided by an endocrinologist or a general internist in concert with a patient's primary care doctor) within the first year of diagnosis is associated with improved outcomes after the first year for adults with diabetes mellitus treated as outpatients.

Design: Population-based cohort study using linked administrative data.

Setting: The province of Saskatchewan, Canada.

Sample: 24 232 adults newly diagnosed with diabetes mellitus between 1991 and 2001.

Method: The primary outcome was all-cause mortality. Analyses used multivariate Cox proportional hazards models with time-dependent covariates, propensity scores and case mix variables (demographic, disease severity and comorbidities). In addition, restriction analyses examined the effect of specialist care in low-risk subgroups.

Results: The median age of patients was 61 years, and over a mean follow-up of 4.9 years 2932 (12%) died. Patients receiving specialty care were younger, had a greater burden of comorbidities, and visited doctors more often before and after their diabetes diagnosis (all p< or =0.001). Compared with patients seen by primary care doctors alone, patients seen by specialists and primary care doctors were more likely to receive recommended treatments (all p< or =0.001), but were more likely to die (13.1% v 11.7%, adjusted hazard ratio (HR) 1.17, 95% confidence interval (CI) 1.08 to 1.27). This association persisted even in patients without comorbidities or target organ damage (adjusted HR 1.16, 95% CI 1.01 to 1.34).

Conclusion: Specialty care was associated with better disease-specific process measures but not improved survival in adults with diabetes cared for in ambulatory care settings.