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:

Effect of patient withdrawal on a study evaluating pharmacist management of hypertension . STUDY OBJECTIVES To examine potential threats to internal and external study validity caused by differential patient withdrawal from a randomized controlled trial evaluating pharmacist management of hypertension , to compare the characteristics of patients who withdrew with those of patients who completed the study , and to identify characteristics that predispose patients to withdraw from hypertension management . DESIGN Prospective , randomized , comparative study . SETTING Network of primary care clinics . PATIENTS Four hundred sixty-three patients with a diagnosis of hypertension and a last documented systolic blood pressure of 160 mm Hg or greater and/or diastolic blood pressure of 100 mm Hg or greater . INTERVENTION Patients were randomly allocated to the pharmacist intervention or usual-care ( control ) group . Those in the pharmacist intervention group were collaboratively managed by a primary care clinical pharmacy specialist and their primary care provider . Patients in the control group received usual care from only their primary care provider . MEASUREMENTS AND MAIN RESULTS Of the 463 patients , 191 ( 41 % ) withdrew from the study after randomization and 272 ( 59 % ) completed the study . Patients who withdrew from the pharmacist intervention group were similar to patients who withdrew from the usual-care group with respect to age , sex , insurance status , and chronic conditions . Patients who smoked or had commercial insurance were more likely to withdraw from the study than the other participants . However , multivariate analysis of all variables , when adjusted for the effect of the intervention , revealed that insurance status was the only variable associated with a heightened probability of withdrawal ( p=0.002 ) . CONCLUSION Although this study had a high withdrawal rate , between-group patient characteristics remained balanced . Therefore , internal validity was preserved , and outcomes from the study groups could be reliably compared . A lack of significant differences between patients who withdrew versus those who completed , with the exception of insurance status , suggests that external validity was not jeopardized .
{"Intervention": ["received usual care from only their primary care provider", "pharmacist management of hypertension", "collaboratively managed by a primary care clinical pharmacy specialist and their primary care provider", "pharmacist intervention", "usual-care ( control ) group"], "Outcome": ["withdraw", "insurance status", "withdrawal"], "Participant": ["463", "191", "272", "patient withdrawal on a study", "Four hundred sixty-three patients", "a last documented systolic blood pressure", "diastolic blood pressure", "hypertension"]}