“Spirometric” lung age reference equations: A narrative review

The aim of the present paper was to conduct a narrative review of the published norms of the “spirometric” lung-age (SLA). A literature search which covered the period 1970 to June 2017, was conducted using the Pubmed. The search strategy had used the following MeSH words: “Spirometry”[Majr]) AND “Aging”[Majr]. Six original studies have reported equations predicting SLA for adults aged 18-90 years [USA (n = 2), Japan (n = 2); Australia (n = 1) and Tunisia (n = 1)]. Their sample sizes varied from 125 to 15238, with a total of 32334 volunteers (11788 men). Several models of norms were developed. They included one (often, FEV1) or more spirometric data in addition to one (often, height) or more anthropometric data. All studies have validated their norms in additional one or more groups, with satisfactory results. Only three authors have proposed algorithms to interpret SLA. All studies presented several limitations concerning the sample size and/or representation, the age distribution, the use of old spirometric data and/or equipment, the application of old spirometric methods, and especially mathematical and statistical flaws.