Fig. 4: Standardized leukocyte telomere length (TL) measured by qPCR demonstrates wider interquartile range variation in pulmonary fibrosis (PF) and decreases with increasing age.

A Age-stratified mean values of TL measurements increase within quartiles (Q) from the first quartile (Q1) to the fourth quartile (Q4) for 2046 subjects with PF and 5808 control subjects. Median TL for each race (White red, Black gray, Hispanic orange, and Asian green) stratified by sex (male = squares, female = triangles) among the B Control population (HRS); and C PF population); statistical test: generalized linear regression of sex-stratified median TL across racial/ethnic groups. R² (the coefficient of determination), RMSE (root mean squared error), and P value reported for each subgroup. D Shorter TL below the median (TL₅₀) has greater prevalence with increasing age across all racial groups in the HRS control population (dashed lines), but this association was stronger in White and Black subjects with PF (solid lines). Subjects with PF (White n = 1613, Black, n = 162, Hispanic, n = 187, Asian, n = 70). Control subjects (White n = 4319, Black, n = 779, Hispanic, n = 614, Asian, n = 96). Other racial groups [n = 14] are not included in the graphs above. TL depicted are observed minus expected (O–E; age and gender-adjusted). Purple dotted line = fitted values for females and black dashed line = fitted values for males.