Abstract: Searches identified 5116 unique papers; we retrieved 827 for full screening. In this review, we included 105 studies from 115 papers, in which 10,302 participants were randomized. Mainly as a result of updating the search in July 2015, 38 papers are awaiting classification. Sixty-one of the 105 studies measured the outcome pain, 14 behavioural recovery, 58 length of stay and 49 negative affect. Participants underwent a wide range of surgical procedures, and a range of psychological components were used in interventions, frequently in combination. In the 105 studies, appropriate data were provided for the meta-analysis of 38 studies measuring the outcome postoperative pain (2713 participants), 36 for length of stay (3313 participants) and 31 for negative affect (2496 participants). We narratively reviewed the remaining studies (including the 14 studies with 1441 participants addressing behavioural recovery). When pooling the results for all types of intervention there was low quality evidence that psychological preparation techniques were associated with lower postoperative pain (SMD -0.20, 95% confidence interval (CI) -0.35 to -0.06), length of stay (mean difference -0.52 days, 95% CI -0.82 to -0.22) and negative affect (SMD -0.35, 95% CI -0.54 to -0.16) compared with controls. Results tended to be similar for all categories of intervention, although there was no evidence that behavioural instruction reduced the outcome pain. However, caution must be exercised when interpreting the results because of heterogeneity in the types of surgery, interventions and outcomes. Narratively reviewed evidence for the outcome behavioural recovery provided very low quality evidence that psychological preparation, in particular behavioural instruction, may have potential to improve behavioural recovery outcomes, but no clear conclusions could be reached. Generally, the evidence suffered from poor reporting, meaning that few studies could be classified as having low risk of bias. Overall,we rated the quality of evidence for each outcome as ‘low’ because of the high level of heterogeneity in meta-analysed studies and the unclear risk of bias. In addition, for the outcome behavioural recovery, too few studies used robust measures and reported suitable data for meta-analysis, so we rated the quality of evidence as `very low'. The evidence suggested that psychological preparation may be beneficial for the outcomes postoperative pain, behavioural recovery, negative affect and length of stay, and is unlikely to be harmful. However, at present, the strength of evidence is insufficient to reach firm conclusions on the role of psychological preparation for surgery. Further analyses are needed to explore the heterogeneity in the data, to identify more specifically when intervention techniques are of benefit. As the current evidence quality is low or very low, there is a need for well-conducted and clearly reported research.

Plain-language summary: We included studies of adults who received planned surgery with general anaesthesia. We looked at seven psychological preparation techniques: procedural information (information about what, when and how processes will happen); sensory information (what the experience will feel like and what other sensations they may have, e.g. taste, smell); behavioural instruction (telling patients what they need to do); cognitive intervention (techniques that aim to change how people think); relaxation techniques; hypnosis; and emotion-focused interventions (techniques that aim to help people to manage their feelings). The psychological preparation had to be delivered before surgery for the study to be included in the review. We included studies that looked at the effect of psychological preparation on pain, behavioural recovery, length of stay and negative emotion after surgery (within one month). Studies were included in the review up to the search date of 4 May 2014. We updated the search on 7 July 2015 and will incorporate the 38 studies found in this later search when the review is updated. We included 105 studies from 115 papers, with 10,302 participants taking part. Sixty-one studies measured the outcome pain, 14 behavioural recovery, 58 length of stay and 49 negative emotion. In accordance with the review protocol, we did not record details about funding sources. In this review we included 105 studies, which were reported in 115 papers. A total of 10,302 participants were randomized in these studies. For pain, length of stay and negative emotion we combined numerical findings from the studies. We found that psychological preparation before surgery seemed to reduce pain and negative emotion after the operation and may reduce the time spent in hospital by around half a day but the quality of the evidence was low. Also, the studies used many different psychological preparation techniques (often in different combinations) so it was not possible to discover which techniques were better. We could not statistically combine numerical findings for behavioural recovery because few studies provided sufficient details and studies used different ways of measuring how quickly people returned to usual activities. In reviewing the studies, we found that psychological preparation, in particular behavioural instruction, may have the potential to improve behavioural recovery. However, the quality of this evidence was very low. We looked at the effect of psychological preparation on pain, behavioural recovery, length of stay and negative emotion in this review and did not find evidence to suggest that psychological preparation might lead to harm in these outcomes. However, as we did not look at other outcomes it is possible that we did not identify potential harm. Many studies were poorly reported, so we could not be confident that findings were reliable. For this reason and because of the large variation in psychological techniques, types of surgery and measures used, we graded the quality of the evidence as `low' for the outcomes pain, negative emotion and length of stay; we cannot be confident that these techniques help patients to recover from surgery. For behavioural recovery, we further downgraded the quality of the evidence to `very low' because of problems with measurement and reporting of the outcome.