| Methods |
Trial design: randomised, double‐blind, placebo and normal care controlled study.
Randomisation procedure: acetoaminophen, placebo or nothing was packaged in numbered envelopes, the numbers generated by a computer random number generator. Patients were assigned a number and attached envelope.
Allocation concealment: good.
Blinding: adequate for the intervention and placebo groups, but not possible for the usual care group who received no 'medication'. The outcome assessors (radiologists) were blinded.
Drop‐outs: accounted for.
Intention‐to‐treat analysis: none. Analysis was on the 259 of the 265 who completed the study. 6 participants did not complete a questionnaire.
Country: USA |
| Participants |
A consecutive sample of 541 women attending Breast Cancer Detection Centre for screening mammography were invited to participate in the study, 325 agreed to do so, but 60 had a change of appointment time so were ineligible. A total of 265 women participated in the study and were randomised. However, 6 of those who completed the study were ineligible because of failing to complete the questionnaire, uncertain analgesic intake, or withdrawal from the study.
258 of the 259 women were accounted for at the end of the study. No explanation was given for the withdrawal. 7.8% (n = 20) of women had breast lump detected by registered nurse before the mammogram was taken and these women were still included in the study. No information was given on whether these women were aware of the presence of a breast lump at the time of the screening mammogram.
In the study population: age range 29‐90 years; mean age 53 years; 98% Caucasian; 80% College (university) educated.
This sample believed to be representative of women scheduled at any time of year but not representative of the general USA population.
Women were excluded from the study if they had difficulty understanding or communicating in English, a history of breast cancer, sensitivity to acetoaminophen, liver dysfunction, were pregnant or had taken pain relief in the previous 24 hours. |
| Interventions |
Group 1: acetoaminophen (n = 88).
Group 2: placebo (n = 85).
Group 3: no intervention ‐ usual care (n = 86).
Women received acetoaminophen or placebo 42 to 103 minutes (mean 62 minutes) before mammogram. |
| Outcomes |
1) Discomfort expected and discomfort experienced with the mammogram. Discomfort was marked on a 100 mm VAS with 0 indicating no discomfort.
2) The authors stated that none of the mammograms was judged as inadequate in any of the groups but did not give any information about whether the image quality was actually assessed. |
| Notes |
A well educated population, 98% Caucasian, so not representative of the USA general population.
Less than 50% of those initially invited participated in the study, raising the possibility of non‐response bias.
Inclusion of 20 women with breast lumps could affect this study, especially if these women were aware of this finding before their mammogram, when it might increase anxiety and pain levels during the examination. Furthermore, these mammograms would be more diagnostic than screening mammograms, which could affect the radiologists' approach and the criteria used in assessing these mammograms. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment? |
Low risk |
A ‐ Adequate |
