Pain
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The aim of this study was to examine whether mean data from categorical pain intensity and visual analogue scales for both pain intensity and relief could be used reliably to derive dichotomous outcome measures for meta-analysis. Individual patient data from randomised controlled trials of single-dose analgesics in acute postoperative pain were used. The methods used were as follows: data from 132 treatments with over 4700 patients were used to calculate mean %maxSPID (categorical pain intensity), %maxVAS-SPID (visual analogue pain intensity) and %maxVAS-TOTPAR (visual analogue pain relief); these were used to derive relationships with the number of patients who achieved at least 50% pain relief (%maxTOTPAR). ⋯ Reports of randomised trials of analgesics frequently describe results of studies in the form of mean derived indices, rather than using discontinuous events, such as number of proportion of patients obtaining at least 50% pain relief. Because mean data inadequately describe information with a non-normal distribution, combining such mean data in systematic reviews may compromise the results. Showing that dichotomous data can reliably be derived from mean SPID, VAS-SPID and VAS-TOTPAR as well as TOTPAR data in previously published acute pain studies makes much more information accessible for meta-analysis.
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The analgesic effectiveness and safety of oral tramadol were compared with standard analgesics using a meta-analysis of individual patient data from randomised controlled trials in patients with moderate or severe pain after surgery or dental extraction. Calculation of %maxTOTPAR from individual patient data, and the use of > 50%maxTOTPAR defined clinically acceptable pain relief. Number-needed-to-treat (NNT) for one patient to have > 50%maxTOTPAR compared with placebo was used to examine the effectiveness of different single oral doses of tramadol and comparator drugs. ⋯ There was a dose response with tramadol, tending towards higher incidences at higher doses. Single-patient meta-analysis using more than half pain relief provides a sensitive description of the analgesic properties of a drug, and NNT calculations allow comparisons to be made with standard analgesics. Absolute ranking of analgesic performance should be done separately for postsurgical and dental pain.