Effectiveness of influenza vaccination on hospitalization outcomes among older patients with diabetes

In older populations admitted for diabetes, limited evidence suggests that influenza vaccination protects against hospitalization outcomes.

This study pooled 27,620 hospitalizations recorded for elderly diabetes patients from the Beijing Elderly Influenza Vaccination Information Registration Database (2013-2018) and the Beijing Urban Employee Basic Medical Insurance Database (2013-2018). Generalized linear regression and propensity score matching were conducted to estimate the effects of influenza vaccination on hospitalization outcomes (in-hospital all-cause mortality, readmission, length and costs of hospitalization), adjusting for measurable confounding factors. The low influenza period (May-July) was used as a reference period to adjust for unmeasured confounding factors during the peak influenza period (November-January).

In propensity score matching, influenza vaccination in peak influenza period could reduce the risk of in-hospital death (OR: 0.47[0.22,0.97]) and readmission (OR: 0.70[0.60,0.81]), length of hospitalization (β: -1.32[-1.47, -1.17]) and medical costs (GMR: 0.90[0.88,0.92]). After adjusting for unmeasured confounding factors, influenza vaccination was associated with 17% (ratio of ORs: 0.83 [0.69, 1.02]) lower risk of readmission and shorter length of hospitalization (difference in β: -0.23 [-0.62, 0.16]). The subgroup analyses showed that male patients with older age and poorer health conditions could benefit more after influenza vaccination.

Influenza vaccination could significantly improve hospitalization outcomes in elderly diabetic patients. This provides evidence supporting free influenza vaccination policies for vulnerable populations in low- and middle-income countries.