Patterns of primary care and mortality among patients with schizophrenia or diabetes: a cluster analysis approach to the retrospective study of healthcare utilization
1 VERDICT Research, South Texas Veterans Health Care System, San Antonio TX, USA
2 Department of Psychiatry, University of Texas Health Science Center at San Antonio, San Antonio TX, USA
3 Department of Epidemiology and Biostatistics, University of Texas Health Science Center at San Antonio, San Antonio TX, USA
4 Department of Family & Community Medicine, University of Texas Health Science Center at San Antonio, San Antonio TX, USA
5 Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio TX, USA
6 SMITREC Research, Veterans Administration Ann Arbor Healthcare System, Ann Arbor MI, USA
7 Department of Psychiatry, University of Michigan, Ann Arbor MI, USA
BMC Health Services Research 2009, 9:127 doi:10.1186/1472-6963-9-127Published: 26 July 2009
Patients with schizophrenia have difficulty managing their medical healthcare needs, possibly resulting in delayed treatment and poor outcomes. We analyzed whether patients reduced primary care use over time, differentially by diagnosis with schizophrenia, diabetes, or both schizophrenia and diabetes. We also assessed whether such patterns of primary care use were a significant predictor of mortality over a 4-year period.
The Veterans Healthcare Administration (VA) is the largest integrated healthcare system in the United States. Administrative extracts of the VA's all-electronic medical records were studied. Patients over age 50 and diagnosed with schizophrenia in 2002 were age-matched 1:4 to diabetes patients. All patients were followed through 2005. Cluster analysis explored trajectories of primary care use. Proportional hazards regression modelled the impact of these primary care utilization trajectories on survival, controlling for demographic and clinical covariates.
Patients comprised three diagnostic groups: diabetes only (n = 188,332), schizophrenia only (n = 40,109), and schizophrenia with diabetes (Scz-DM, n = 13,025). Cluster analysis revealed four distinct trajectories of primary care use: consistent over time, increasing over time, high and decreasing, low and decreasing. Patients with schizophrenia only were likely to have low-decreasing use (73% schizophrenia-only vs 54% Scz-DM vs 52% diabetes). Increasing use was least common among schizophrenia patients (4% vs 8% Scz-DM vs 7% diabetes) and was associated with improved survival. Low-decreasing primary care, compared to consistent use, was associated with shorter survival controlling for demographics and case-mix. The observational study was limited by reliance on administrative data.
Regular primary care and high levels of primary care were associated with better survival for patients with chronic illness, whether psychiatric or medical. For schizophrenia patients, with or without comorbid diabetes, primary care offers a survival benefit, suggesting that innovations in treatment retention targeting at-risk groups can offer significant promise of improving outcomes.