Because of high cost, persons with hemophilia in many developing countries cannot afford adequate treatment. For example, many persons with hemophilia in India and China are only rarely treated with factor replacement in response to bleeds, and as a result many have developed significant arthropathy and disability. A pilot study in China estimated the mean Hemophilia Joint Health Score (HJHS) at 13.1 (SD 9.03) suggesting that these children had highly prevalent, severe joint disease. The lack of relationship between the HJHS and treatment history suggests overall inadequate therapy.

The proposed study will quantify the burden of arthropathy, physical disability, and quality of life (QoL) in boys with hemophilia in Brazil - where comprehensive treatment is just beginning to be widely available. This study will also provide an opportunity to compare these outcomes to those observed in Canada, where the dominant therapy has become life-long prophylaxis.

In order to quantify the burden of illness in hemophilia, and to study the response to different treatments, it is necessary to have quantitative outcome measures of high validity and reliability. The International Prophylaxis Study Group (IPSG - chair Dr. Victor Blanchette) was established in 2001 with the stated purpose of developing and testing outcome tools for this purpose. The group has developed a magnetic resonance imaging (MRI) score for quantifying arthropathy (representing the domain of structure and function domain in the ICF framework), a quantitative physical examination score, and the Hemophilia Joint Health Score or HJHS, to replace the older and less sensitive World Federation of Hemophilia (WFH) score (representing the domain of structure and function in the ICF). In addition Canadian investigators have also developed a quality of life measure for boys with hemophilia, the Canadian Hemophilia Outcomes Kids' Life Assessment Tool or CHO-KLAT (representing the domain of participation in the ICF).

We will use these tools, and other validated measures, to begin to determine the burden of hemophilia in Brazil and compare it to the burden of disease in Canada. Additionally, we will use this study to demonstrate the validity of these tools in the Brazilian population.

Inclusion criteria

• Hemophilia A or B moderate or severe as determined by serum factor activity ≤ 5%
• Age 7 - 18 yrs. inclusive
• At least one parent or guardian fluent in written Portuguese or English and able to complete the study outcome questionnaires.

Exclusion criteria

• None (Children with inhibitors will be allowed into the study for 2 reasons: i) our study aims to document the health of persons with hemophilia in a generalizable way, ii) not all children will have had inhibitor testing done.)

Participants will be a representative (random) sample of individuals from the comprehensive hemophilia treatment centres at HCFMUSP and SickKids. Boys between the ages of 7 and 18 years (inclusive) will be identified from the clinic ledgers at each of the centres. Using a computer generated random number list, proportionately stratified for Hemophilia A and B, and for moderate and severe disease (based on the baseline clinic proportions)