You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Outcome", "Participant", "Intervention"].

Please return the output as a JSON object of the format: {"Participant" : ["patients with COPD", ...], "Intervention" : ["Atenolol", ...], "Outcome" : ["blood pressure", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Initial abstinence status and contingency management treatment outcomes : does race matter ? OBJECTIVE Limited research has evaluated African American substance users ' response to evidence-based treatments . This study examined the efficacy of contingency management ( CM ) in African American and White cocaine users . METHOD A secondary analysis evaluated effects of race , treatment condition , and baseline cocaine urine sample results on treatment outcomes of African American ( n = 444 ) and White ( n = 403 ) cocaine abusers participating in one of six randomized clinical trials comparing CM to standard care . RESULTS African American and White patients who initiated treatment with a cocaine-negative urine sample remained in treatment for similar durations and submitted a comparable proportion of negative samples during treatment regardless of treatment type ; CM was efficacious in both races in terms of engendering longer durations of abstinence in patients who began treatment abstinent . Whites who began treatment with a cocaine positive sample remained in treatment longer and submitted a higher proportion of negative samples when assigned to CM than standard care . African Americans who initiated treatment with a cocaine positive sample , however , did not remain in treatment longer with CM compared with standard care , and gains in terms of drug use outcomes were muted in nature relative to Whites . This interaction effect persisted through the 9-month follow-up period . CONCLUSIONS CM is not equally effective in reducing drug use among all subgroups , specifically African American patients who are using cocaine upon treatment entry . Future research on improving treatment outcomes in this population is needed .
{"Intervention": ["contingency management ( CM )", "CM", "contingency management", "standard care"], "Outcome": ["contingency management ( CM )"], "Participant": ["403", "cocaine users", "cocaine abusers", "444"]}