Table 3.

Analgesic usea by time in placebo (n = 99) and nortriptyline (n = 99) groupsb

AnalgesicPlaceboNortriptylineAdjusted odds ratio (95% CI)
Baseline14 weeksDifferenceBaseline14 weeksDifference
Mean proportion of days when analgesic was not taken
  Paracetamol, %52.557.64.353.062.69.11.55 (1.03 to 2.37)
  NSAID, %66.669.14.161.673.911.53.91 (2.49 to 6.16)
  Opioid, %81.582.80.676.980.84.61.60 (0.86 to 2.99)
Mean standard analgesic tablet count on days when analgesic was takenAdjusted rate ratio (95% CI)
  Paracetamol, n4.24.20.03.63.5−0.10.97 (0.92 to 1.03)
  NSAID, n6.46.1−0.37.46.7−0.70.85 (0.80 to 0.90)
  Opioid, n7.06.6−0.45.96.80.90.98 (0.90 to 1.07)
  • a One pill is defined as the equivalent of 500 mg paracetamol, 200 mg ibuprofen, or 15 mg codeine.

  • b Of the 205 participants enrolled in the study (n = 103 placebo, n = 102 intervention), seven (n = 4 placebo, n = 3 intervention) did not complete a medication diary at week 14 and therefore could not be included in the analgesic analysis. Four withdrew or were lost to follow-up (n = 1 placebo, n = 3 intervention) and had no week 14 data, a further three (all placebo) completed the week 14 assessment (WOMAC questionnaire) but did not complete the medication diary. NSAID = non-steroidal anti-inflammatory drug.