| Study characteristics |
| Methods |
This trial was a single‐centre, randomised, double‐blind, placebo‐controlled, add‐on, cross‐over design for 2 periods of 1 week each |
| Participants |
Pain model: patients on morphine therapy due to neuropathic cancer pain. Mean age: 67.1 years. 16 patients were randomised and 15 completed the 2 periods of treatment. 6/16 patients were female. Participants with at least moderate pain and stable doses of morphine in the last 2 days were included. Participants that were users of treatment failure of antidepressants were not included in the study. |
| Interventions |
Patients received 25 mg of amitriptyline or equivalent drops of placebo at night for 3 days plus 50 mg for the following 4 days. Patients were in stable dose of morphine. |
| Outcomes |
Outcomes reported: pain intensity in a 0 to 10 scale. Adverse effects, mood and sleep were recorded in 0 to 3 scales. Patient’s preference was recorded at the end of the study. |
| Notes |
Small size trial (16) and small period of treatment (only 1 week) |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Method of randomisation is not stated |
| Allocation concealment (selection bias) |
Unclear risk |
Not enough information to determine if the allocation was concealed |
| Blinding of participants and personnel (performance bias)
All outcomes |
Unclear risk |
Insufficient information |
| Blinding of outcome assessment (detection bias)
All outcomes |
Unclear risk |
If the same assessors who noticed drug‐related side effects were also assessing pain outcomes, they might be biased |
| Incomplete outcome data (attrition bias) |
Low risk |
Very low dropout rate |
| Selective reporting (reporting bias) |
Low risk |
Pain score is standard in pain clinical trials. The trial does not state if it was registered. |
| Other bias |
High risk |
Fewer than 50 participants per period and < 8 weeks duration of trial |
