Incidence, risk factors, and viral etiology of community-acquired acute lower respiratory tract infection among older adults in rural north India

Abstract

Background There are limited data on incidence, risk factors and etiology of acute lower respiratory tract infection (LRTI) among older adults in low- and middle-income countries. Methods We established a cohort of community dwelling older adults ≥60 years and conducted weekly follow-up for acute respiratory infections (ARI) during 2015-2017. Nurses assessed ARI cases for LRTI, collecting combined nasal/throat swabs from all LRTI cases and an equal number of age- and sex-matched asymptomatic neighbourhood controls. Swabs were tested for influenza viruses, respiratory syncytial virus (RSV), human metapneumovirus (hMPV), and parainfluenza viruses (PIV) using polymerase chain reaction. LRTI and virus-specific LRTI incidence was calculated per 1000 person-years. We estimated adjusted incidence rate ratios (IRR) for risk factors using Poisson regression and calculated etiologic fractions (EF) using adjusted odds ratios for detection of viral pathogens in LRTI cases vs controls. Results We followed 1403 older adults for 2441 person-years. LRTI and LRTI-associated hospitalization incidences were 248.3 (95% confidence interval (CI) = 229.3-268.8) and 12.7 (95% CI = 8.9-18.1) per 1000 person-years. Persons with pre-existing chronic bronchitis as compared to those without (incidence rate ratio (IRR) = 4.7, 95% CI = 3.9-5.6); aged 65-74 years (IRR = 1.6, 95% CI = 1.3-2.0) and ≥75 years (IRR = 1.8, 95% CI = 1.4-2.4) as compared to 60-64 years; and persons in poorest wealth quintile (IRR = 1.4, 95% CI = 1.1 - 1.8); as compared to those in wealthiest quintile were at higher risk for LRTI. Virus was detected in 10.1% of LRTI cases, most commonly influenza (3.8%) and RSV (3.0%). EF for RSV and influenza virus was 83.9% and 83.6%, respectively. Conclusion In this rural cohort of older adults, the incidence of LRTI was substantial. Chronic bronchitis was an important risk factor; influenza virus and RSV were major viral pathogens.

Evaluating the Increased Burden of Cardiorespiratory Illness Visits to Adult Emergency Departments During Flu and Bronchiolitis Outbreaks in the Pediatric Population: Retrospective Multicentric Time Series Analysis

“…This hypothesis assumes that older adults in decompensation are infected with RSV. This has been confirmed in the recent literature, which clearly shows that this virus is found in these clinical situations [33,34] and that it is responsible for a non-negligible fraction of cases [35] on the one hand. On the other hand, this hypothesis implies that RSV circulates in an epidemic mode and that its circulation, when it exists, is massive.…”

Risk factors and medical resource utilization in US adults hospitalized with influenza or respiratory syncytial virus in the Hospitalized Acute Respiratory Tract Infection study

“…In 2016, an estimated 2.38 million LRTI‐associated deaths occurred across all age groups worldwide 1 . Influenza and respiratory syncytial virus (RSV) are among the most common causes of LRTIs during typical (i.e., non‐pandemic) endemic seasons, 2 with influenza causing an estimated 1 billion infections 3 and RSV causing an estimated 64 million acute respiratory infections 4 globally each year. A systematic analysis from the Global Burden of Diseases, Risk Factors, and Injuries study found that influenza caused ~500,000 deaths and RSV caused 250,000 deaths annually worldwide 5 .…”

Multisite surveillance for influenza and other respiratory viruses in India: 2016–2018

“…Among SARI cases, influenza virus was detected in 27% of pregnant women, 12.4% of cases with pre-existing chronic diseases and 12.7% adults �60 years. Studies from India during the same period had shown high incidence of influenza in pregnant women (68 to 90 per 10,000 pregnant women months) and older adults (influenza associated lower respiratory infection incidence:7.9 per 1000 person years) [19,20]. High burden of influenza among these WHO Strategic Advisory Group of Experts (SAGE) target groups suggests that value proposition of influenza vaccination and early interventions (early detection and antiviral treatment) among these groups need to be explored by the country.…”