Trends in Cause-Specific Outcomes Among Individuals With Type 2 Diabetes and Heart Failure in the United Kingdom, 1998-2017

Abstract

IMPORTANCE The phenotype of individuals with type 2 diabetes and heart failure (HF) is changing. Successful public health interventions for type 2 diabetes mean that patients more frequently present with HF without a prior ischemic event, which is likely to change outcomes, but trends in cause-specific outcomes are unknown. OBJECTIVE To investigate cause-specific outcomes and trends associated with type 2 diabetes among individuals with incident HF. DESIGN, SETTING, AND PARTICIPANTS This cohort study used UK primary care data, linked to hospital admissions and mortality, for 87 709 patients with incident HF from 1998 to 2017. Patients were 30 years or older and observed to death or July 31, 2017. Data analysis was conducted in March and April 2019. EXPOSURE Preexisting type 2 diabetes at diagnosis of HF. Individuals with type 1 diabetes were excluded. MAIN OUTCOMES AND MEASURES All-cause, cardiovascular (CVD), and non-CVD unplanned hospitalizations and mortality rates. RESULTS Of 87 709 patients with HF (43 173 [49.2%] women; 78 211 [89.2%] white), 20 858 (23.8%) had type 2 diabetes (median [interquartile range] age, 78.0 [70.0 to 84.0] years), and 66 851 (76.2%) had no diabetes (median [interquartile range] age, 80.0 [72.0 to 86.0] years). In patients with HF, type 2 diabetes was associated with an increase in the risk of unplanned hospital admission (adjusted incidence rate ratio for CVD hospitalizations: 1.24; 95% CI, 1.19 to 1.30; for non-CVD hospitalizations: 1.26; 95% CI, 1.22 to 1.30) and an increase in the risk of mortality (adjusted hazard ratio for CVD mortality: 1.06; 95% CI, 1.02 to 1.10; for non-CVD mortality: 1.24; 95% CI, 1.19 to 1.29). Age-standardized mortality risk at 1 year was 35.6% (95% CI, 35.1% to 36.1%) in the type 2 diabetes group vs 29.2% (95% CI, 29.0% to 29.5%) in the group with no diabetes. During the study period (ie, 1998 to 2017), associations of type 2 diabetes with hospitalization and mortality rates decreased for CVD outcomes but not for non-CVD outcomes. Age-adjusted hospitalization rates during the first year following HF diagnosis increased similarly for both groups over time (eg, HF with type 2 diabetes, 1998 to 2001: 133.3 per 100 person-years; 95% CI, 102.2 to 105.4 per 100 person-years; 2012 to 2015: 152.5 per 100 person-years; 95% CI, 145.5 to 159.5 per 100 person-years; P for difference in trend = .06), but trends diverged by cause. For example, hospitalizations for HF decreased for patients with type 2 diabetes at approximately the same annual rate (−2.2%; 95% CI, −3.9% to −0.5%) as they increased for those without diabetes (1.7%; 95% CI, 1.1% to 2.3%; P for difference in trend < .001). After 2004, a trend emerged showing a greater increase in non-CVD admissions among patients with HF and type 2 diabetes than among patients with no diabetes (2.3% [95% CI, 0.9% to 3.6%] vs 1.1% [95% CI, 0.8% to 1.4%]). In contrast to hospitalization rates, mortality rates reduced over time in both groups, but the reduction was greater among those with type 2 diabetes than without (−1.4% [95% CI, −1.8% to −0.9%] vs −0.7% [95% CI, −1.2% to −0.2%]; P for difference in trend < .001). CONCLUSIONS AND RELEVANCE In this study, the higher risk of all cause-specific outcomes and emerging non-CVD trends associated with patients with type 2 diabetes who experienced HF indicated an urgent need for earlier comorbidity management and patient-centered multimorbidity care.