Lilja 1998.

Methods	Randomised parallel group trial.
Participants	55 participants (median age 65 years) undergoing total hip replacement. Intervention group: 9 women, 13 men; control group: 8 women, 20 men. Inclusion criteria: aged < 75 years. Exclusion criteria: none stated. Location: Angelholm, Sweden.
Interventions	Intervention group (n = 22) given extended formalised information concerning pre‐ and postoperative procedures by an anaesthetic nurse for 30 minutes the day before surgery. Control group (n = 28) informed about pre‐ and postoperative routines by a ward nurse.
Outcomes	Anxiety (Hospital Anxiety and Depression Scale (0‐21 points) higher score represented greater anxiety); pain (VAS, ranging from 0 (no pain) to 10 (worst imaginable pain)); serum cortisol (radioimmunoassay). Participants were assessed preoperatively and 1 and 3 days postoperatively.
Notes	Aim of the trial was to evaluate effects of extended preoperative information on perioperative stress. 5 participants withdrew post‐randomisation.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "... were randomized into two groups..." Comment: sequence generation not described.
Allocation concealment (selection bias)	Unclear risk	Comment: method of allocation not described.
Blinding (performance bias and detection bias) Self‐reported outcomes	Low risk	Quote: "To avoid interventional bias, the patients were only informed that a trial was in progress, but were not informed about the aim and the design of the trial."
Blinding (performance bias and detection bias) Objective outcomes	Low risk	Quote: "The randomized design of the trial was kept from all personnel who came into contact with the patients except for the anaesthetic nurses who participated in the extended information. These nurses did not participate in any way in the postoperative registrations of stress, anxiety and pain."
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: reasons are given for the withdrawal of the 5 participants after randomisation and their distribution between the 2 groups; it is not clear whether some of these participants underwent surgery. The study authors stated there were no other exclusions but it was not clear if there were any missing data within each analysis because the sample size was not reported.
Selective reporting (reporting bias)	High risk	Comment: trialists only reported mean values of each group with no measures of variation for all outcomes (and noted that the differences between groups on all outcomes were not statistically significant. Attempts to retrieve this missing data from trialists were unsuccessful. In addition, all outcomes listed in the methods were reported in the results, but without the trial protocol, it is unclear whether any other outcomes were measured but not reported based on the results.
Other bias	Low risk	Comment: no other sources of bias identified.