Table 1: Paracetamol rescue medication in randomised controlled osteoarthritis trials in selected recent publications.

TrialDoses allowed (mg)Primary or secondary endpointResultsRemarks

Frestedt et al. [20]325 mg per tablet with 1-2 tablets to be taken every 4–6 hours as needed for painNoNo significant differences between the two groups for rescue medication consumption at any single time point or over timeNo figures given

Karlsson et al. [21]≤4000 mg/day could be taken as for unacceptable pain for more than 24 hoursNoRescue medication usage was significantly better than under placeboNo figures given

Jacquet et al. [22]Tablets equivalent to 500 mg paracetamol alone or combined with weak opiates (e.g., coproxamol or coparein)Main outcome measure 500 mg paracetamol equivalent tablets per week (PET/week) measured each monthSingle-component Paracetamol (number of users, tablets/week ± SD) Phytalgic 12 (21 ± 14.7) Placebo 15 (15.4 ± 10.4)Add-on study to the usual symptomatic medication (analgesics and/or NSAIDs)

Krüger et al. [23]500 mg tablets; intake was permitted if necessary due to pain but not 48 hours before visitsSecondary endpoint, recorded daily by the patient in the diary and checked by the physician at each visit (pill counting)Low acetaminophen consumption; differences between the groups not significantNo figures given

Puopolo et al. [24]For breakthrough pain, if needed; no dose reportedSecondary endpoint; use was determined by tablet countsPatients treated with etoricoxib or ibuprofen used significantly less paracetamol than those receiving placebo for breakthrough pain Paracetamol use in the etoricoxib and ibuprofen groups was similarFigures not listed in the table of the key secondary results 

Reginster et al. [25]325 mg tablets; use was restricted (it was not permitted during the initial 2 weeks of treatment) and recordedNoNo data shown

Sawitzke et al. [26]Up to 4 g daily could be taken, but patients were instructed not to take this drug within 24 h of a follow-up visit to allow for accurate measurement of their current pain levelsNoThe use of paracetamol averaged 570 mg daily. The lowest use was in the celecoxib (465 mg) group and the highest use in the placebo group (645 mg) Rank order of rescue drug use (least to greatest) exactly paralleled to that of the primary efficacy outcome

Schnitzer et al. [27]500 mg tablets for use in case of increased OA pain, with a maximum accepted dose of 2000 mg/dayAdditional efficacy measuresAverage daily tablets use in the placebo group 1.77 versus 1.33 to 1.43 in the naproxcinod groups and 1.34 in the naproxen group

Yang et al. [28]Maximum of 4 g/dayNoNo data shownAsked to stop analgesics at least 1 week before completing the questionnaires and visiting their treating orthopaedic surgeon

Thorne et al. [29]325 mg to 650 mg every 4 h to 6 h as requiredSecondary end point; compared for each treatment, based on the average daily consumption, and was summarized each weekSignificantly greater use during the placebo phase (3.4 ± 3.6 tablets/day) than during the CR tramadol phase (2.4 ± 3.1 tablets/day)