What factors should influence the dosage and interval of prophylactic treatment in patients with severe haemophilia A and B?

Primary prophylaxis implementation and long-term joint outcomes in Swedish haemophilia A patients

INTRODUCTION

Primary prophylaxis is the gold standard in severe haemophilia A (SHA) but time to escalate the prophylaxis regimen varies.

AIM

Assess prophylaxis implementation and long-term joint health outcomes in SHA with primary prophylaxis.

METHODS

Adult male patients born after 1980, with SHA on primary prophylaxis, started before the age of 3 years and second joint bleed, and no history of FVIII inhibitors, were enrolled. Repeated joint-health examinations were performed with HJHS or HEAD-US; VERITAS-PRO assessed adherence.

RESULTS

Thirty patients were enrolled with, at inclusion, median age 33.5 years, annualized bleed rate and joint bleed rate 0, and FVIII consumption 4232 IU/kg/year, respectively. The median age was 1.2 years, at prophylaxis start once weekly with a median FVIII dose of 47.7 IU/kg, and 1.7 years, by the time escalation to a final regimen had occurred, with a median infusion frequency of thrice weekly and FVIII dose 41.7 IU/kg, respectively. Older age correlated with later transition to escalated prophylaxis (p < .001). Longer time to escalated prophylaxis correlated to more bleeds (p < .001). Median HJHS increased slowly, reaching 4 at 35-40 years. HJHS at 15-20 years correlated with higher HJHS afterwards. Median total HEAD-US score was 1 and correlated with HJHS (p < .001). Median VERITAS-PRO score was 36, indicating good treatment adherence.

CONCLUSION

Primary prophylaxis is effective but does not completely prevent the gradual development of arthropathy in SHA. Joint assessments with HJHS should start at an early age, as they correlate with arthropathy in later life. Prophylaxis escalation should proceed expeditiously to prevent bleeds.

Low-dose prophylaxis and its impact on the health of haemophilia patients

BACKGROUND AND OBJECTIVES

There is convincing evidence to show that low-dose prophylaxis (LDP) results in reduction in annualized bleeding rate (ABR) and better health-related quality of life (HRQoL) compared with on-demand or episodic treatment (ET) in haemophilia patients. The aim is to review various LDP protocols practised for the treatment of haemophilia, specifically in resource-limited countries.

METHODS

A literature survey was made of articles published in English language in PubMed and EMBASE without any time limit using keywords 'low dose', 'prophylaxis' and 'haemophilia' in different combinations.

RESULTS

A total of 19 reports involving LDP in patients with haemophilia were included in this review. Almost all studies reported reduction in ABR, improvement in joint function, pain and HRQoL compared with ET, but this did not fully translate into significant improvement in structural arthropathy already caused by earlier bleeds, suggesting that LDP may be less or ineffective in either stopping or reversing the damage. Individualized dose escalation protocols based on pharmacokinetic (PK) or clinical parameters were found to be superior to fixed LDP protocols and cost-effective compared with standard dose protocols.

CONCLUSION

The developing countries can initiate LDP as the first step of prophylaxis, but certainly this should not be the final goal of the health care system in any country. Due to the complex pathophysiological mechanisms underlying haemophilic arthropathy, long-term data on LDP in haemophilia patients are warranted.

Bayesian Forecasting Utilizing Bleeding Information to Support Dose Individualization of Factor VIII

Bayesian forecasting for dose individualization of prophylactic factor VIII replacement therapy using pharmacokinetic samples is challenged by large interindividual variability in the bleeding risk. A pharmacokinetic‐repeated time‐to‐event model‐based forecasting approach was developed to contrast the ability to predict the future occurrence of bleeds based on individual (i) pharmacokinetic, (ii) bleeding, and (iii) pharmacokinetic, bleeding and covariate information using observed data from the Long‐Term Efficacy Open‐Label Program in Severe Hemophilia A Disease (LEOPOLD) clinical trials (172 severe hemophilia A patients taking prophylactic treatment). The predictive performance assessed by the area under receiver operating characteristic (ROC) curves was 0.67 (95% confidence interval (CI), 0.65–0.69), 0.78 (95% CI, 0.76–0.80), and 0.79 (95% CI, 0.77–0.81) for patients ≥ 12 years when using pharmacokinetics, bleeds, and all data, respectively, suggesting that individual bleed information adds value to the optimization of prophylactic dosing regimens in severe hemophilia A. Further steps to optimize the proposed tool for factor VIII dose adaptation in the clinic are required.

Impact of prophylaxis on health-related quality of life of boys with hemophilia: An analysis of pooled data from 9 countries

BACKGROUND

Prophylaxis reduces the frequency of bleeds in boys with severe hemophilia and is the standard care for their management in resource-abundant countries. The effect of prophylaxis on Health-Related Quality of Life (HRQoL) has not been established, because the sample sizes of most studies are too small to explore the relationship of multiple factors that influence HRQoL.

METHODS

The aim of this study was to assess the impact of hemophilia severity and treatment regimen on HRQoL and to establish the minimum important difference (MID) using the international level of score distributions. HRQoL data were pooled from 7 studies across 9 countries. HRQoL was measured using the Canadian Hemophilia Outcomes-Kids' Life Assessment Tool (CHO-KLAT). A mixed-effect linear regression analysis was employed to assess the impact of prophylaxis on the CHO-KLAT score.

RESULTS

Data from 401 boys with hemophilia were analyzed (57.6% severe hemophilia and 57.6% receiving prophylaxis). The model revealed that receiving prophylaxis was significantly associated with higher HRQoL (regression coefficient 8.5, 95% confidence interval [CI] 3.9-13.1). Boys with severe hemophilia had a significantly lower HRQoL as compared to boys with moderate and mild hemophilia whose CHO-KLAT scores were 7.0 and 6.6 points higher, respectively. There was a significant interaction between treatment and disease severity (P = 0.023), indicating prophylaxis has the most significant impact in boys with severe hemophilia. Based on these pooled data, the MID of the CHO-KLAT was established at 6.5.

CONCLUSIONS

This study confirms the positive effect of prophylaxis on HRQoL in boys with hemophilia in a real-world setting and provides initial benchmarks for interpreting HRQoL scores based on use of the CHO-KLAT instrument.

A randomized study of very low-dose factor VIII prophylaxis in severe haemophilia - A success story from a resource limited country

INTRODUCTION

Current factor prophylaxis strategy practised in developed countries is not feasible in resource constraint developing countries like India.

AIM

The aim of this study was to investigate the efficacy and safety of very low-dose factor prophylaxis in India.

METHODS

Children of 1-10 years of age with severe haemophilia were randomized to Prophylaxis group and Episodic (On demand) group. Children in prophylaxis group received very low-dose factor VIII (FVIII) concentrate, i.e. 10 units kg(-1) body weights on 2 days a week. Episodic group received factor concentrate in standard recommended doses. The study period was 11.5 months.

RESULTS

In total 21 children were enrolled in this study, 11 assigned to prophylaxis and 10 to episodic group. Children on prophylaxis had 11 joint bleeds in comparison to 57 joint bleeds in episodic group. Mean number of haemarthrosis per patient per month were 0.08 (0.08 ± 0.13) in prophylaxis group compared to 0.48 (0.48 ± 0.34) in episodic group (P < 0.05). Total FVIII consumption was 87.51 and 56.32 units kg(-1) month(-1) in prophylaxis and episodic group respectively (P = ns). Overall median hospital emergency visits were 1 day in prophylaxis group and 9 days in episodic group (P ≤ 0.05). Median days of absenteeism from school were 25 days in episodic group and 3 days in prophylaxis group (P < 0.05). No significant complications were noted in prophylaxis group and compliance was 98%.

CONCLUSION

To conclude, low-dose FVIII prophylaxis is cost effective, efficacious and a safe method of preventing joint bleeds and consequent joint damages.