The HAQ-II (download here) is a 10-item questionnaire used to measure disability or physical function in patients with rheumatic diseases. To score, just sum all the scores of each question (a minimum of 7 must be answered), and divide by the total number of questions answered to get a value between 0 (minimal loss of function) and 3 (completely disabled). For more information, please refer to our paper:
Wolfe F, Michaud K, Pincus T. Development and validation of the health assessment questionnaire II: a revised version of the health assessment questionnaire. Arthritis & Rheumatism. 2004;50(10):3296-305.