We read the article by Clair et al reporting an association between housing and biological ageing with great interest.1 This publication built on preliminary work on how the physically built environment associates with DNA methylation (DNAm)2 by focusing on DNAm age (also known as epigenetic age or epigenetic clock).

However, we note the authors investigated only one DNAm age measure: DunedinPACE. The authors argued that DunedinPACE was selected due to its greater association with mortality and morbidity than other measures of epigenetic age. While the paper they cited did indeed show that DunedinPACE predicted mortality better than the Hannum, Horvath and Levine clocks,3 it did not compare the performance of DunedinPACE to GrimAge, a more recently developed epigenetic clock for mortality.

Associations between exposures and DNAm age vary widely according to which clocks are used. Hence, we sought to …