Although researchers found significant negative associations between red cell distribution width (RDW) and measures of lung function — including forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and FEV1/FVC, they concluded that RDW was not a sensitive marker of impaired lung function for those in the general population aged 50 to 64. These were among findings of research recently published in Respiratory Medicine.

The study analysis was based on whole blood samples and spirometry data obtained from subjects aged 50 to 64 years as part of SCAPIS (CArdioPulmonary bioImage Study), a Swedish study. Researchers looked at the associations of RDW with spirometry (in 5767 patients), diffusing capacity (in 5496 patients), and impulse oscillometry (in 5598 patients). The potential relationships between lung function measures and RDW were then explored via linear regression and general linear models.

Results indicated that FEV1 and FEV1/FVC were significantly and inversely association with RDW. Impulse oscillometry data analysis showed that RDW was significantly associated with pulmonary resistance. Significant associations between RDW and carbon monoxide diffusion were found only among smokers. Yet analysis of never-smokers showed that FVC was significantly associated with RDW in this subgroup, thus indicating a relationship between RDW and lung function that is independent of smoking.

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Investigators noted that when lung function was in the normal range, it seemed to have only a small effect on RDW. They hypothesized that RDW could be an unspecific marker for poor general health, which also could be related to low lung function.

The researchers concluded that “RDW is not likely to be a sensitive marker of impaired lung function in middle-aged individuals in the general population.” They also stressed that the “underlying mechanisms for high RDW and lower pulmonary function are still unclear.”


Pan J, Zaigham S, Persson M, Borné Y, Wollmer P, Engström G. The associations between red cell distribution width and lung function measures in a general population. Respir Med. 2021;185:106467. doi: 10.1016/j.rmed.2021.106467