HONGKONG citizens could end up carrying another passbook in their bags and briefcases - but this one would be a record of their health rather than their bank balance. The Health and Medical Development Advisory Committee intends to promote the idea of a health passbook among doctors and the public to ensure better record-keeping and more accessible patient information. According to committee member Dr Chan Kai-ming, the passbook would contain basic details of a person's medical history, allergies, vaccinations and, possibly, medication taken. ''The detailed information would still be kept at the clinics and hospitals,'' he said. In the case of patients with conditions such as diabetes, the passbook would ensure swift and accurate diagnosis, he said. The Department of Health presently gives chronically ill patients attending specialist clinics a basic medical record. But the committee would like to see this extended to the entire population.