Incidence, risk factors, and viral etiology of community-acquired acute lower respiratory tract infection among older adults in rural north India
Rakesh Kumar, Lalit Dar, Ritvik Amarchand, Siddhartha Saha, Kathryn E. Lafond, Debjani Ram Purakayastha, Ramesh Kumar, Avinash Choudekar, Giridara Gopal, Shivram Dhakad, Venkatesh Vinayak Narayan, Abhishek Wahi, Reshmi Chhokar, Stephen Lindstrom, Brett Whitaker, Aashish Choudhary, Ankita Dey, Anand Krishnan
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: 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.