Estimates of the global, regional, and national morbidity, mortality, and aetiologies of lower respiratory tract infections in 195 countries: a systematic analysis for the Global Burden of Disease Study 2015

Abstract

SummaryBackgroundThe Global Burden of Diseases, Injuries, and Risk Factors (GBD) Study 2015 provides an up-to-date analysis of the burden of lower respiratory tract infections (LRIs) in 195 countries. This study assesses cases, deaths, and aetiologies spanning the past 25 years and shows how the burden of LRI has changed in people of all ages.MethodsWe estimated LRI mortality by age, sex, geography, and year using a modelling platform shared across most causes of death in the GBD 2015 study called the Cause of Death Ensemble model. We modelled LRI morbidity, including incidence and prevalence, using a meta-regression platform called DisMod-MR. We estimated aetiologies for LRI using two different counterfactual approaches, the first for viral pathogens, which incorporates the aetiology-specific risk of LRI and the prevalence of the aetiology in LRI episodes, and the second for bacterial pathogens, which uses a vaccine-probe approach. We used the Socio-demographic Index, which is a summary indicator derived from measures of income per capita, educational attainment, and fertility, to assess trends in LRI-related mortality. The two leading risk factors for LRI disability-adjusted life-years (DALYs), childhood undernutrition and air pollution, were used in a decomposition analysis to establish the relative contribution of changes in LRI DALYs.FindingsIn 2015, we estimated that LRIs caused 2·74 million deaths (95% uncertainty interval [UI] 2·50 million to 2·86 million) and 103·0 million DALYs (95% UI 96·1 million to 109·1 million). LRIs have a disproportionate effect on children younger than 5 years, responsible for 704 000 deaths (95% UI 651 000–763 000) and 60.6 million DALYs (95ÙI 56·0–65·6). Between 2005 and 2015, the number of deaths due to LRI decreased by 36·9% (95% UI 31·6 to 42·0) in children younger than 5 years, and by 3·2% (95% UI −0·4 to 6·9) in all ages. Pneumococcal pneumonia caused 55·4% of LRI deaths in all ages, totalling 1 517 388 deaths (95% UI 857 940–2 183 791). Between 2005 and 2015, improvements in air pollution exposure were responsible for a 4·3% reduction in LRI DALYs and improvements in childhood undernutrition were responsible for an 8·9% reduction.InterpretationLRIs are the leading infectious cause of death and the fifth-leading cause of death overall; they are the second-leading cause of DALYs. At the global level, the burden of LRIs has decreased dramatically in the last 10 years in children younger than 5 years, although the burden in people older than 70 years has increased in many regions. LRI remains a largely preventable disease and cause of death, and continued efforts to decrease indoor and ambient air pollution, improve childhood nutrition, and scale up the use of the pneumococcal conjugate vaccine in children and adults will be essential in reducing the global burden of LRI.FundingBill & Melinda Gates Foundation.

Recurrent lower respiratory tract infections in children

“…Children younger than 5 years old are worst affected by lower respiratory infections, with 704 000 deaths each year and more than 6 million disability-adjusted life years (DALYs) worldwide 2. There is no consensus on how many episodes of lower respiratory infection are “too many” and require further investigation.…”

“…Acute respiratory infections account for about a third of all paediatric consultations to primary care and 8-18% of acute hospital admissions in the UK 12. Children, especially preschool children, may have up to 6-10 viral colds a year 13.…”

Effect of acute respiratory illness on short‐term frailty status of older adults in Nakhon Phanom, Thailand—June 2015 to June 2016: A prospective matched cohort study

“…Limited data exist regarding the impact of acute respiratory infections on frailty status in non‐institutionalized, community‐dwelling older adults . In particular, there are few studies examining frailty status post‐acute respiratory infection in an Asian setting where intergenerational households are common and morbidity and mortality are high relative to other global regions . We conducted a matched cohort study to evaluate the effect of acute respiratory illness (ARI) on the short‐term frailty status of community‐dwelling adults aged ≥65 years in Thailand.…”

Reply to Alonso et al. “Bangladesh and Rwanda: Cases of high burden of influenza in tropical countries?”

“…The IHME methods for estimating global influenza deaths focus on attributing influenza virus infections to lower respiratory tract infection deaths,25 while we focused on associating influenza to a wider case definition of acute respiratory infections. The IHME approach attributes a death to a single pathogen or condition as primary cause of death, which requires careful interpretation as some viral pathogens, such as influenza, have been observed to exacerbate some chronic medical conditions, such as asthma or chronic lung and cardiac conditions.…”

“…The methods used by IHME to estimate influenza‐associated deaths are different from what many influenza researchers utilize when they estimate mortality burden. A comparison of the IHME approach to other methods used to estimate global influenza deaths is further discussed in Iuliano et al26 Lastly, IHME mentions in their limitations that their estimates are not representative of non‐hospitalized disease burden,25 which we measured using community surveys to capture deaths occurring outside of hospitals. Thus, we would expect our estimates to be higher than the IHME estimates.…”