Risk of pneumonia and pneumococcal disease in people hospitalized with diabetes mellitus: English record-linkage studies

BackgroundThe risk of invasive pneumococcal disease is higher in people with diabetes mellitus than those without. People with diabetes should be considered for routine pneumococcal immunization. This policy has been in place in England for more than a decade. We aimed to estimate, at the population level, the current scale of excess risk of pneumococcal disease in patients with diabetes, and whether the risks have decreased in recent years with the introduction of a pneumococcal vaccine. MethodsWe used two data sets of linked hospital admission and death recordsthe Oxford Record Linkage Study (1963-1998) and all-England linked hospital episode statistics (1999-2011). As a measure of relative risk, we calculated the rate ratio of pneumococcal disease in cohorts of people hospitalized with diabetes compared with cohorts without a record of diabetes. ResultsThe risk of pneumococcal disease in patients hospitalized with diabetes mellitus has declined a little, but it is still high. The all-ages rate ratio in England declined from 1.92 (95%CI 1.89-1.94) in 1999-2002 to 1.68 (95%CI 1.65-1.71) in 2007-2011. In people aged under 60years, rate ratios were higher and their decline was more substantial: rate ratios declined from 3.37 (95%CI 3.28-3.46) in 1999-2002 to 2.33 (95%CI 2.21-2.45) in 2007-2011. ConclusionsPatients admitted to hospital with diabetes mellitus remain at increased risk of pneumococcal infection despite a national immunization policy. Possible explanations for the elevated risk include low vaccine uptake or low effectiveness of available vaccine. Clinicians should be aware of the risk of pneumococcal infection in people with diabetes.