Considerable differences may exist between objective and subjective measures of adherence to prophylaxis in patients with hemophilia, according to a cross-sectional study.
The results highlight the effect of social desirability bias in self-reported measures of adherence and differences in conceptual understanding of adherence between hemophilia experts and patients.
Vanessa Giroto Guedes, MPH, of the Federal University of Rio de Janeiro and colleagues studied 29 male patients with hemophilia who received prophylactic treatment between August 2015 and January 2016. The study was conducted at two hemophilia treatment centers in São Paulo.
Self-perceived adherence, measured using the estimated number of clotting factor concentrate doses missed over the previous dispensing interval, was compared with an objective estimate of adherence, measured using the number of vials returned by study participants. The findings were published in.
Patient interviews were conducted during regularly scheduled visits to the treatment facility. The team collected self-perceived adherence data using a 5-point Likert scale, scored from very poor to very good adherence.
After analysis, the researchers found no significant correlation between the objective categorization of adherence and self-perceived extent of adherence (correlation coefficient, 0.10; 95% confidence interval, –0.28 to 0.46; P = .61).
Additionally, there was no significant correlation between the categorization of adherence measured using the proportion of missed doses evaluated objectively and using participants’ self‐reports (correlation coefficient, 0.32; 95% CI, –0.01 to 0.59; P = .11).
“Participants’ self-reported perception of adherence was almost three times more likely to be rated as very good or good than it was for the objective assessment of adherence to be classified as adherent or suboptimally adherent,” the researchers wrote.
No funding sources were reported. One coauthor reported providing consultancy services for manufacturers of therapies for hemophilia. The others reported no conflicts of interest.
SOURCE: Guedes VG et al. Haemophilia. 2019 Jul 19. .