Association of Hemophilia a Inhibitor Status and Patient-Reported Outcomes with Work Productivity and Health-Related Quality of Life

Introduction: Persons with hemophilia suffer from recurrent bleeds, especially hemarthrosis, which results in joint damage. Hemophilia inhibitor status impacts bleeding, which is associated with acute and chronic pain. To better characterize the impact of inhibitor status, we compared patient-reported outcomes (bleed rate, pain, and joint health), work productivity and activity impairment (WPAI), and health-related quality of life (HRQoL) by inhibitor status, and investigated the correlation of patient-reported outcomes with WPAI and HRQoL.

Methods: The U.S. Hematology Utilization Group Studies Part VIII prospectively collected data to examine the cost and burden of hemophilia in persons with hemophilia A (PwHA) aged ≥2 years obtaining care at four federally-supported hemophilia treatment centers. From April 2019 to May 2021 we enrolled PwHA with and without inhibitors at a 1:2 ratio. Parents/adult participants completed a survey at enrollment to collect sociodemographic and clinical characteristics, self-reported bleeds in the last month, pain, and joint stiffness (5-item scale). We also measured WPAI and HRQoL using EQ-5D-3L. Clinical chart review documented hemophilic severity, inhibitor level and treatment regimen. Participants were classified into three groups: 1) active inhibitor (inhibitor titer ≥1.0 Bethesda Units (BU) six months prior to enrollment), 2) tolerized inhibitor (history of inhibitor titer ≥1.0 BU, immune tolerance induction (ITI) and/or currently using factor VIII for prophylaxis), and 3) no inhibitor. Patient-reported data were compared across these groups using Chi-square tests for categorical variables and generalized linear models for continuous variables. Association of bleeds, pain, and joint stiffness with HRQoL and WPAI were assessed using Pearson correlation.

Results: Among 80 PwHA enrolled, 9 (11%) had active inhibitors, 22 (27.5%) had tolerized inhibitors, and 49 (61.3%) had no inhibitors. Mean age was 24.9±14.3 (standard deviation) years, 66.3% were adults, 87.5% had severe hemophilia, and 87.5% used prophylaxis. Mean age of the non-inhibitor group (29.3±13.5) was older than the tolerized inhibitor group (16.3±9.5 years, p<0.05) or the active inhibitor group (21.9±19.1, p>0.05). The non-inhibitor group had a lower rate of severe hemophilia (81.6%) or prophylactic treatment (81.6%) than those in the active (100%) or tolerized groups (95.5%, p=0.13). Larger proportions of participants with active inhibitors (66.7%) and no inhibitors (57.1%) reported having bleeds in the last month compared to those with tolerized inhibitors (22.7%, p=0.01). Participants without inhibitors had a greater mean number of bleeding episodes (1.09±standard error (SE) 0.26 vs. 0.23±0.38, p=0.03), specifically joint bleeds (0.58±0.16 vs. 0.08±0.24, p=0.03,) than the tolerized group. Those with active inhibitors reported significantly higher mean joint stiffness scores (35.1±2.6 vs. 27.5±1.9, p=0.006) or more joint pain (77.8% vs. 54.5%, p=0.23) than the tolerized group. Mean EQ-5D index score was significantly lower in the active inhibitor group (0.79±SE (0.07) than in the tolerized group (0.96±0.05, p=0.03). Joint bleeding, chronic pain, and joint stiffness were negatively correlated with the EQ-5D visual analogue scale, and index scores (all correlation coefficients |r|>0.43, all p<0.001). Number of bleeds and the joint stiffness score in children were positively correlated with their parents' level of impairment while working (r=0.41, p=0.04; r=0.62, p=0.001) and overall work impairment (r=0.41, p=0.046; r=0.60, p=0.002). Joint bleeding, chronic pain, and joint stiffness in adults were positively correlated with proportion of work time missed (r=0.31, p=0.03; r=0.39, p=0.006; r=0.48, p=0.0004), overall work impairment (r=0.37, p=0.007; r=0.41, p=0.003; r=0.42, p=0.002), and activity impairment (r=0.33, p=0.02; r=0.63, p<0.0001; r=0.59, p<0.0001), respectively.

Conclusions: This study is limited to a small sample skewed toward a younger age in the tolerized inhibitor group. PwHA in the active and no inhibitor groups experienced greater clinical burden as measured by bleeds compared to the tolerized group. Those with active inhibitor displayed lower HRQoL scores than the tolerized inhibitor group. Bleeds, chronic pain and joint stiffness were inversely correlated with HRQoL, resulting in lower work productivity and activity.

Figure 1

View largeDownload slide

Figure 1

View largeDownload slide

Close modal