Incidence and prevalence of interstitial lung diseases worldwide: a systematic literature review

Abstract

Interstitial lung disease (ILD) is a collective term representing a diverse group of pulmonary fibrotic and inflammatory conditions. Due to the diversity of ILD conditions, paucity of guidance and updates to diagnostic criteria over time, it has been challenging to precisely determine ILD incidence and prevalence. This systematic review provides a synthesis of published data at a global level and highlights gaps in the current knowledge base. Medline and Embase databases were searched systematically for studies reporting incidence and prevalence of various ILDs. Randomised controlled trials, case reports and conference abstracts were excluded. 80 studies were included, the most described subgroup was autoimmune-related ILD, and the most studied conditions were rheumatoid arthritis (RA)-associated ILD, systemic sclerosis associated (SSc) ILD and idiopathic pulmonary fibrosis (IPF). The prevalence of IPF was mostly established using healthcare datasets, whereas the prevalence of autoimmune ILD tended to be reported in smaller autoimmune cohorts. The prevalence of IPF ranged from 7 to 1650 per 100 000 persons. Prevalence of SSc ILD and RA ILD ranged from 26.1% to 88.1% and 0.6% to 63.7%, respectively. Significant heterogeneity was observed in the reported incidence of various ILD subtypes. This review demonstrates the challenges in establishing trends over time across regions and highlights a need to standardise ILD diagnostic criteria.PROSPERO registration number: CRD42020203035.

Keywords: Asbestos Induced Lung Disease; Clinical Epidemiology; Interstitial Fibrosis; Systemic disease and lungs.

Figure 1

Geographical distribution of publications included.

Figure 2

Studies reporting non-IPF prevalence as percentage of study population. DM, dermatomyositis; HP, hypersensitivity pneumonitis; IIP, idiopathic interstitial pneumonia; ILD, interstitial lung disease; LAM, lymphangioleiomyomatosis; MCTD, mixed connective tissue disorder; multiC, multicentre; PLCH, pulmonary langerhans cell histiocytosis; PM, polymyositis; RA, rheumatoid arthritis; reg, registry; single, single centre; SSc, systemic sclerosis. Details on the study population, sample size and ILD diagnosis methods are summarised in online supplemental tables E1–E31.

Figure 3

Studies reporting ILD incidence, grouped by ILD subgroups. ICD-9-CM, International Classification of Disease, Ninth Revision, Clinical Modification; ILD, interstitial lung disease; py, person-years; RA, rheumatoid arthritis; SSc, systemic sclerosis. Ɨ Narrow silicosis definition used: Medicare beneficiaries with any claim that included ICD-9-CM code 502, pneumoconiosis due to other silica or silicates, listed in any position during 1999–2014, with at least one inpatient, skilled nursing or home health agency claim, or at least two outpatient provider claims within 365 days of each other and cases with a chest X-ray or CT scan 30 days before or 30 days after a silicosis claim. Details on the study population, sample size and ILD diagnosis methods are summarised in online supplemental tables E1–E31.