Factors associated with physical activity in young people with haemophilia A on prophylaxis

Physical activity (PA) is influenced by numerous factors, and the literature describing why people with haemophilia (PWH) are physically active or not is inconclusive.

To investigate factors associated with PA (mean min/day in light (LPA), moderate (MPA), vigorous (VPA) and total PA, and proportion meeting World Health Organization (WHO) weekly moderate-to-vigorous (MVPA) recommendations) among young PWH A.

Forty PWH A on prophylaxis from the HemFitbit study were included. PA was measured using Fitbit devices and participant characteristics were collected. Potential factors associated with PA were investigated by univariable linear regression models for continuous PA outcomes, and descriptively for teenagers meeting/not meeting WHO MVPA recommendations only, because all except one adult met PA recommendations.

Mean age (n = 40) was 19.5 years (SD 5.7). Annual bleeding rate was nearly zero and joint scores were low. We found an increase of four min/day in LPA (95% confidence interval (CI) 1-7) per year increase in age. Participants with 'Haemophilia Early Arthropathy Detection with Ultrasound' (HEAD-US) score ≥1 engaged in mean 14 min/day less MPA (95% CI -23.2 to -3.8), and 8 min less VPA (95% CI -15.0 to -0.4) compared to participants with HEAD-US score 0. Teenagers who met PA recommendations had slightly better joint status compared to those who did not meet recommendations.

These findings indicate that presence of mild arthropathy does not affect LPA but may have a negative impact on PA of higher intensities. Early start of prophylaxis may be an important determinant of PA.