Discussion
We have presented a randomized trial assessing the postsurgical evaluation of patient experiences by asking about pain compared with asking about comfort. It is the only clinical study to assess the effects of assessing pain on postoperative experiences and patient perceptions, using a priori outcomes. This report responds in part to the call for more research into the placebo and nocebo effects of communication and follows on from the landmark research by Lang and colleagues showing that negative suggestions can increase perioperative pain and anxiety. Although this issue has not previously been considered of clinical relevance in the context of assessing pain, there is clear evidence to the contrary in other settings. A previous study has demonstrated that in the assessment of pain after Caesarean section, women are more likely to report pain when asked 'Do you have pain?' compared with when women are asked 'Are you comfortable?' It may be that if patients are asked if they are in pain after operation a 'yes' is more likely, than if questioned 'How are you?' or 'Are you comfortable?' As the use of the 'pain' word in a phrase may lead to the communication functioning as a negative suggestion, we avoided asking about pain and comfort in the same patient by randomizing for comfort and pain yet still asking about different aspects of the postoperative experience in a standardized way.
The key findings of our study show that when comparing VNRS for pain and comfort, lower scores are found for the inverted comfort score than their equivalent pain score. This finding also was shown with the use of VAS at rest and with movement. When women were asked specifically, 'Do you have pain?', an approximately equal number of women reported pain in the two groups. This suggests that women will report pain when directly asked, irrespective of whether it bothers them or needs treating. When women were asked, 'Are you comfortable?', significantly more women in Group C reported that they were comfortable compared with those allocated to Group P. Interestingly, the negative suggestions used in Group P seem to have resulted in an increased number of patients reporting that their postoperative sensations were unpleasant, more bothersome, and perceived as tissue damage and injury rather than healing and recovery (Table 3). Patients allocated to Group P also had more requests for additional analgesia than those participants allocated to Group C. These results are consistent with previous studies suggesting that the use of negative words increase patient pain and anxiety levels.
Surprisingly, more than half of the women in Group P who reported that they had pain also stated that they were comfortable when asked directly, and the majority of these patients neither desired nor required additional analgesia. As suggested previously, our findings clearly demonstrate that asking about pain and pain scores alone do not give healthcare providers enough clinically useful information to decide if patients are receiving adequate postoperative analgesia or require an intervention. Indeed, enquiring about whether patients are actually bothered by pain, and whether they desire any treatment for it, may be more useful questions to ask when considering whether an intervention for postoperative pain is indicated. Consistent with previous research in other settings, our avoidance of negative suggestions when using comfort scores rather than standard pain scores has not shown any observable harms. This suggests that the use of comfort scores may have an advantage over traditional postoperative assessments using pain scores. Our findings appear to be consistent with recent research on pain processing regarding modulation of the anterior cingulate cortex when negative suggestions are used and how this affects pain processing and influences patients' clinical experience. Although more women allocated to Group P preferred to be asked about their pain scores rather than their comfort scores, many were unsure of their reasons. Some women did report 'familiarity' and 'ease of use' as reasons for their preference.
There were a number of limitations to this study. First, there are no exact antonyms to pain and it could be argued that the word 'comfort' may not be a suitable antonym for 'pain'. In other contexts, one might question whether our primary outcome to assess pain severity with the degree of comfort is a primary outcome at all rather than a description of two separate assessment methods. However, in the context of assessing postoperative pain and in the laboratory, it appears likely that as soon as pain is mentioned, it is likely to focus the patient on pain and associate the perception of sensations in a negative way. Our statistical comparison between the 'pain' and 'comfort' groups relied upon an inversion of comfort scores such that the anchors are reversed, that is, 'most pain' becomes translated to 'least comfortable' and 'least pain' gets translated to 'most comfortable'. The inverse transformation used in this study appears to have more than just face validity for the anchors, as they were asked in a way that focused the patient on the sensations associated with the Caesarean wound. Although uncommon, similar inverted scales have been used previously in the context of a 0–10 'pain relief' scale, where '0' was no pain relief and '10' was maximum pain relief. However, it is difficult to be certain whether a particular pain score say, 3 of 10 pain really corresponds to a 7 of 10 for comfort. This would be an interesting area for future research. The style and expression of the assessors could have potentially impacted on our study findings. However, the highly structured nature of the words used in intervention and control groups, the limited number of investigators asking the questions, and the excellent internal validity in terms of randomization and allocation concealment should have minimized any risk of bias in this regard.
Women were questioned at a separate time to the usual ward rounds by obstetric and anaesthetic teams and our study does not address how patients were questioned by doctors and nurses about their pain before the assessment in this study. However, when assessing pain, clinical differences in approach would be expected to have been equally distributed across groups by the randomization process. The researchers conducted interviews in a standardized and structured manner but were not blinded to participant group allocation. In addition, there were no expectations of showing a difference between pain and comfort scores by assessors which should have minimized any potential for bias. Blinding of assessors should be a consideration in future studies investigating the effects on pain when it is measured.
This study may be considered to have ethical challenges as our study protocol had ethics committee approval for written informed consent to be obtained after the postoperative assessment. As with other research investigating subconscious patient responses to communication, patient consent before the intervention was thought likely to influence our outcomes of interest. The need for additional pain relief was not tracked over time because of the limited resources available. However, we were able to confirm that all women requesting postoperative analgesia did receive it. Study participants may have responded to the researcher that they did not want additional analgesia, but then sometime later may have asked for analgesia. Neonatal outcomes and maternal complications from Caesarean section could have potentially influenced pain perception, but this was found to be comparable between groups (Table 2). Further details in this regard would be an interesting consideration for future research. The self-funded nature of this study did not allow for multiple visits or prolonged follow-up which would be an interesting aspect for future research in assessing whether the use of negative language in the assessment of pain influences the length of stay in hospital, nausea and vomiting, or even the incidence of chronic pain. It would also be interesting to investigate whether these results are applicable to women who are potentially experiencing postoperative pain in other settings such as after general surgery. Further investigation involving male patients and those in private and non-tertiary hospitals would also be of interest. Further research into patient preferences may facilitate further our understanding of the power of words when interacting with patients.
Traditionally, it has been suggested that regular assessment and measures of pain makes pain visible and thus improves management, particularly in acute pain. Our trial findings suggest that questioning patients about their pain and pain scores after Caesarean section adversely affects patient reports of their postoperative experiences, possibly by focusing the patient on their pain and therefore exacerbating the unpleasantness and bothersome nature of the postoperative wound. This suggests that the belief that repeated use of pain scores making pain visible may also be explained as an effect of repeated negative suggestions increasing its incidence, its exacerbation, or both. Similarly, the view that recording pain intensity as 'the fifth vital sign' can improve acute pain management is based on relatively poor evidence (Level III-3). Our study findings suggest that not only is the response to pain questioning dependent on how postoperative questions are phrased but that current testing may be adversely affecting patients' postoperative experiences. The evidence from the current and previous studies suggests a naive simplicity to expect that one could reliably guide appropriate pain management by reducing something as complex as the experience of pain to a single number.
It would seem reasonable to conduct post-anaesthesia interviews using a more permissive open question structure initially such as 'How are you feeling' rather than 'How much pain have you got?' Avoidance of the use of the 'pain' or similar negative words until they are expressed by the patient may be a consideration in its assessment and management. If future research confirms our findings, the continued encouragement of using pain scores in the context of postoperative pain as the fifth vital sign should be questioned, and possibly replaced with more neutral or positive language. As with pain relief ratings, inverted comfort scores are likely to be related to, but distinct from, changes in pain intensity. Although they read somewhat lower than pain scores, inverted comfort scores may be one possible way of avoiding the effects of negative suggestions when assessing postoperative pain after Caesarean section.