Representative drug susceptibility patterns for guiding design of retreatment regimens for XXXX .

@entity1 @entity378 @entity6371
BACKGROUND: There is no gold standard on how national @entity378 programs should design retreatment regimens. Often drug susceptibility testing (DST) is not available for all @entity1 , and representative DST patterns in @entity1 populations are used to guide therapy. OBJECTIVES: To examine DST patterns in different @entity1 populations based on previous treatment and to estimate the number of effective anti- @entity378 agents in several retreatment regimens. METHODS: We reviewed DST results from @entity1 treated with individualized regimens in Peru between January 1998 and July 2004. We stratified @entity1 into four groups based on previous treatment exposure from Group 1 who had failed only one regimen to Group 4 who had failed three regimens. We compared resistance frequencies across the four groups. In Groups 1 and 3, the number of likely effective agents under six possible retreatment regimen scenarios was estimated. RESULTS: Resistance to second-line drugs was significantly higher in groups with more previous courses of treatment. A few retreatment regimens could be identified that would allow at least 80% of @entity1 to receive at least four likely effective drugs. CONCLUSION: Because it is associated with resistance frequencies, previous treatment exposure can serve to guide the design of non-individualized @entity6371 regimens.
