Reported reasons for stopping a drug when treatment was modified. (a) all drugs; (b) by country income category (b-1, low-income; b-2, high-income); (c) by type of treatment failure (c-1, immunological failure; c-2, virological failure; c-3, clinical progression), (d) by time from treatment failure (d-1, up to 90 days; d-2, 91–180 days; d-3, 181 days or more).