Search strategies: Individual patient data meta‐analyses compared with meta‐analyses based on aggregate data. MEDLINE OvidSP (MEDLINE In‐Process & Other Non‐indexed citations and MEDLINE (R)) (1950 to Week 1 January 2016); Embase OvidSP (1980 to Week 1 2016) searched 7 January 2016. 1 (individual patient$ adj6 data).tw. 2 (individual patient$ adj6 report$).tw. 3 (individual patient$ adj6 outcome$).tw. 4 (individual patient$ adj6 level$).tw. 5 ipd.tw. 6 (individual subject$ adj6 data).tw. 7 (individual subject$ adj6 report$).tw. 8 (individual subject$ adj6 outcome$).tw. 9 (individual subject$ adj6 level$).tw. 10 (raw patient$ adj6 data).tw. 11 (raw data adj6 patient$).tw. 12 (raw data adj6 individual$).tw. 13 (raw data adj6 subject$).tw. 14 (raw data adj6 participant$).tw. 15 (individual participant$ adj6 data).tw. 16 (individual participant$ adj6 report$).tw. 17 (individual participant$ adj6 outcome$).tw. 18 (individual participant$ adj6 level$).tw. 19 or/1‐18 20 remove duplicates from 19 The Cochrane Library Issue 1 2016 (includes Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effectiveness, CENTRAL, Cochrane Methodology Register, HTA database, NHS Economic Evaluations Database) – searched 7 January 2016. #1 (individual next patient*):ti,ab near6 data:ti,ab #2 (individual next patient*):ti,ab near6 report*:ti,ab #3 (individual next patient*):ti,ab near6 outcome*:ti,ab #4 (individual next patient*) near6 level*:ti,ab #5 ipd:ti,ab #6 (individual next subject*):ti,ab near6 data:ti,ab #7 (individual next subject*):ti,ab near6 report*:ti,ab #8 (individual next subject*):ti,ab near6 outcome*:ti,ab #9 (individual next subject*):ti,ab near6 level*:ti,ab #10 (raw next patient*):ti,ab near6 data:ti,ab #11 (raw next data):ti,ab near6 patient*:ti,ab #12 (raw next data):ti,ab near6 individual*:ti,ab #13 (raw next data):ti,ab near6 subject*:ti,ab #14 (raw next data):ti,ab near6 participant*:ti,ab #15 (individual next participant*):ti,ab near6 data:ti,ab #16 (individual next participant*):ti,ab near6 report*:ti,ab #17 (individual next participant*):ti,ab near6 outcome*:ti,ab #18 (individual next participant*):ti,ab near6 level*:ti,ab #19 #1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9 or #10 or #11 or #12 or #13 or #14 or #15 or #16 or #17 or #18