Men with psoriatic arthritis, rheumatoid arthritis and axial spondylarthritis have more children and at an earlier age than matched controls: results from a nationwide cohort

Abstract

Objectives: The reproductive health of men with inflammatory joint disease (IJD) has been a topic of debate in recent years, due to conflicting findings in existing research. In this study, we investigated childlessness and number of children per man, according to the joint diseases psoriatic arthritis (PsA), rheumatoid arthritis (RA) and axial spondylarthritis (axSpA). Furthermore, we studied the timing of fathering and risk factors associated with childlessness.

Methods: This is a nationwide, population-based cohort study. Male patients aged 25-65 years with PsA (n=2649), RA (n=1716) and axSpA (n=2766) from the Norwegian Arthritis Registry were individually matched 1:5 with men without IJDs obtained from the National Population Register (n=35 655). Information on children was obtained from the Medical Birth Registry of Norway. Fertility rates were compared between the patient/IJD groups and matched controls.

Results: In all IJD groups, fewer men were childless compared with the control groups (p<0.001). Similarly, the mean number of children per man was higher in all diagnostic groups, and this difference was evident before the IJD diagnosis (p<0.001). AxSpA patients had a slightly higher proportion of childless men compared with patients with PsA (p<0.001). Also, men with IJD were younger than the respective controls when fathering for the first time (p<0.001).

Conclusion: This large nationwide study revealed that men with PsA, RA and axSpA were less childless compared with the general population, a difference that occurred before the onset of the IJD. These findings are novel, suggesting a notable difference in fertility patterns between those with and without IJDs.

Keywords: Arthritis; Arthritis, Psoriatic; Arthritis, Rheumatoid; Axial Spondyloarthritis; Epidemiology.

Figure 1. Selection process for the study population. IJD, inflammatory joint disease; MBRN, Medical Birth Registry of Norway; NAR, Norwegian Arthritis Registry; NPR, National Population Register; PsA, psoriatic arthritis; RA, rheumatoid arthritis; SpA, spondylarthritis.

Figure 2. Years to first child in men with PsA, RA and axSpA compared with control subjects. X-axis starts at 15 years and ends at 55 years. Y-axis is percentage who has not become fathers at the given age, among those ‘at risk’ at the given age.

Figure 3. Mean number of children born per man before and after time of diagnosis in 2021.(a) Age ≤ 40 years old at diagnosis (n=4,084). (b) Age > 40 years old at diagnosis (n=3,047). *Y-axis range from 0-1 child per man in (a) and 0-2 children per man in (b). *The total number of children per man cannot be directly compared across the IJD groups in (a) and (b) as all men in (b) are 40 years old at data extraction in 2021 and represent an older subgroup of patients than in (a). IJD, inflammatory joint disease.