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Background Antipsychotic drugs are the mainstay treatment for schizophrenia, yet they are associated with diverse and potentially dose‐related side effects which can reduce quality of life. For this reason, the lowest possible doses of antipsychotics are generally recommended, but higher doses are often used in clinical practice. It is still unclear if and how antipsychotic doses could be reduced safely in order to minimise the adverse‐effect burden without increasing the risk of relapse. Objectives To assess the efficacy and safety of reducing antipsychotic dose compared to continuing the current dose for people with schizophrenia. Search methods We conducted a systematic search on 10 February 2021 at the Cochrane Schizophrenia Group's Study‐Based Register of Trials, which is based on CENTRAL, MEDLINE, Embase, CINAHL, PsycINFO, PubMed, ClinicalTrials.gov, ISRCTN, and WHO ICTRP. We also inspected the reference lists of included studies and previous reviews. Selection criteria We included randomised controlled trials (RCTs) comparing any dose reduction against continuation in people with schizophrenia or related disorders who were stabilised on their current antipsychotic treatment. Data collection and analysis At least two review authors independently screened relevant records for inclusion, extracted data from eligible studies, and assessed the risk of bias using RoB 2. We contacted study authors for missing data and additional information. Our primary outcomes were clinically important change in quality of life,  rehospitalisations and dropouts due to adverse effects; key secondary outcomes were clinically important change in functioning, relapse, dropouts for any reason, and at least one adverse effect. We also examined scales measuring symptoms, quality of life, and functioning as well as a comprehensive list of specific adverse effects. We pooled outcomes at the endpoint preferably closest to one year. We evaluated the certainty of the evidence using the GRADE approach. Main results We included 25 RCTs, of which 22 studies provided data with 2635 participants (average age 38.4 years old). The median study sample size was 60 participants (ranging from 18 to 466 participants) and length was 37 weeks (ranging from 12 weeks to 2 years). There were variations in the dose reduction strategies in terms of speed of reduction (i.e. gradual in about half of the studies (within 2 to 16 weeks) and abrupt in the other half), and in terms of degree of reduction (i.e. median planned reduction of 66% of the dose up to complete withdrawal in three studies). We assessed risk of bias across outcomes predominantly as some concerns or high risk. No study reported data on the number of participants with a clinically important change in quality of life or functioning, and only eight studies reported continuous data on scales measuring quali...

Background In clinical practice, different antipsychotics can be combined in the treatment of people with schizophrenia (polypharmacy). This strategy can aim at increasing efficacy, but might also increase the adverse effects due to drug–drug interactions. Reducing polypharmacy by withdrawing one or more antipsychotics may reduce this problem, but must be done carefully, in order to maintain efficacy. Objectives To examine the effects and safety of reducing antipsychotic polypharmacy compared to maintaining people with schizophrenia on the same number of antipsychotics. Search methods On 10 February 2021, we searched the Cochrane Schizophrenia Group's Study‐Based Register of Trials, which is based on CENTRAL, CINAHL, ClinicalTrials.Gov, Embase, ISRCTN, MEDLINE, PsycINFO, PubMed and WHO ICTRP. Selection criteria We included randomised controlled trials (RCTs) that compared reduction in the number of antipsychotics to continuation of the current number of antipsychotics. We included adults with schizophrenia or related disorders who were receiving more than one antipsychotic and were stabilised on their current treatment. Data collection and analysis Two review authors independently screened all the identified references for inclusion, and all the full papers. We contacted study authors if we needed any further information. Two review authors independently extracted the data, assessed the risk of bias using RoB 2 and the certainty of the evidence using the GRADE approach. The primary outcomes were: quality of life assessed as number of participants with clinically important change in quality of life; service use assessed as number of participants readmitted to hospital and adverse effects assessed with number of participants leaving the study early due to adverse effects. Main results We included five RCTs with 319 participants. Study duration ranged from three months to one year. All studies compared polypharmacy continuation with two antipsychotics to polypharmacy reduction to one antipsychotic. We assessed the risk of bias of results as being of some concern or at high risk of bias. A lower number of participants left the study early due to any reason in the polypharmacy continuation group (risk ratio (RR) 0.44, 95% confidence interval (CI) 0.29 to 0.68; I 2 = 0%; 5 RCTs, n = 319; low‐certainty evidence), and a lower number of participants left the study early due to inefficacy (RR 0.21, 95% CI 0.07 to 0.65; I 2 = 0%; 3 RCTs, n = 201). Polypharmacy continuation resulted in more severe negative symptoms (MD 3.30, 95% CI 1.51 to 5.09; 1 RCT, n = 35). There was no clear difference between polypharmacy reduction and polypharmacy continuation on readmission to hospital, leaving the study early due to adverse effects, functioning, globa...