Influenza and morbidity and mortality risk in patients in Mexico with systemic arterial hypertension alone or with comorbidities: a retrospective, observational, cross-sectional study from 2014 to 2020

OBJECTIVES

In Mexico, patients with systemic arterial hypertension (SAH) are excluded from the influenza vaccination programme despite their risk of cardiovascular events as influenza-related complications. We investigated the impact of influenza on morbidity and mortality in patients with SAH.

DESIGN

This was a retrospective cross-sectional study that analysed data from early 2014 to mid-2020.

SETTING

Data were obtained from the Influenza Epidemiological Surveillance System in Mexico database.

PARTICIPANTS

32 663 cases of influenza in people aged ≥20 years with a confirmed case of influenza-like illness, severe respiratory infection and/or influenza death were investigated.

PRIMARY AND SECONDARY OUTCOME MEASURES

Influenza deaths, hospitalisation frequency and the impact on hospitalisation and/or death due to influenza by the SAH variate alone and in combination with diabetes, obesity, chronic obstructive pulmonary disease, cardiovascular disease and/or smoking, and by vaccination status were assessed.

RESULTS

The hospitalisation frequency increased with age. Notably, 46.0% (15 033/32 663) of confirmed influenza cases had at least one comorbidity, with SAH (19.2%; 6260/32 663) and obesity (18.7%; 6106/32 663) being the most prevalent. Most confirmed SAH cases (80.8%; 5057/6260) were in those who had not been vaccinated against influenza. There were 3496 deaths due to influenza (mortality rate, 0.69×1 00 000 inhabitants), with the highest rates seen in those aged ≥80 years (80-89 years, 2.0%; ≥90 years, 3.6%). The case fatality rate due to influenza and SAH was significantly higher than those due to influenza without SAH in those aged <50 years, but not in the other age groups (20-29 years, 9.8%, p<0.0005; 30-39 years, 8.2%, p<0.035; 40-49 years, 17.8%, p<0.0005; vs 15.1%-20.0%, p=0.31-0.99 for those aged ≥50 years).

CONCLUSIONS

Our findings support the need to include SAH in public policies of influenza vaccination as a secondary prevention measure to avoid fatal outcomes.

Reasons for non-vaccination against influenza among older adults with hypertension in Brazil: a cross-sectional study

The aim of this study was to estimate the prevalence of non-vaccination against influenza among Brazilian older adults with systemic arterial hypertension and determine the main reasons for non-adherence. A cross-sectional study was conducted using data from older adults (≥ 60 years of age) with hypertension who participated in the 2013 National Health Survey and reported not having been vaccinated against flu over the previous 12 months (n = 1,295). The analyses were performed using the Stata 14.0 software. The data were weighted because of the sampling design. An estimated 3,026,080 older adults with hypertension had not received a flu vaccine over the 12 months prior to the survey (22.6%). No significant associations were found with sex, age group or schooling. The prevalence of unvaccinated older adults was lower in the southern and southeastern regions of Brazil than in the northern and northeastern regions, even after adjusting for age. The prevalence was higher among individuals without private health insurance. The main reasons for non-vaccination were fear of a reaction, rarely having the flu and not believing in the protection of the vaccine. The present findings underscore the need for healthcare professionals to explain to the population the benefits of the vaccine for preventing severe influenza (protective effect and possible reactions) and for secondary prevention of cardiovascular events. Increasing the prevalence of vaccination in older adults with hypertension and other cardiovascular diseases is of fundamental importance within the realm of public health as a strategy for reducing occurrences of complications and deaths associated with influenza.