Effect of preoperative information about pain on postoperative pain experience and patient satisfaction following orthopaedic surgery: A randomised controlled trial.

Background: Preoperative information about pain has been shown to improve postoperative pain perception and reduce postoperative analgesia requirements. However, there is limited data regarding the effect of preoperative counselling in low resource settings. This study aimed at assessing the effect of preoperative information about pain on postoperative pain experience measured as postoperative pain using a verbal numerical rating scale (VNRS) and patient satisfaction with pain management. Methods: A randomised, double blind, controlled trial was done in Mulago National Referral Hospital (MNRH), Kampala. We prospectively enrolled 400 participants aged 18years and above scheduled for elective orthopaedic surgery. The consented patients were randomised to either receive the specic preoperative information about pain or not. The primary end points were postoperative pain score and patient satisfaction. A total of 340 were analysed with 170 in either arm. Secondary analyses where done to determine the factors that were associated with postoperative pain and patient satisfaction. Results: In both arms, the lowest pain score was 0/10 at 0 hours and the highest was 7/10 at 12 hours. A statistically signicant difference between the intervention and control arms for the median pain score at 48hours (4/10 vs. 5/10) P-value= 0.029 was seen but none at 0, 12, 24hours. There was no difference in satisfaction with pain management (P value=0.059). Conclusion: Preoperative information about pain improves postoperative pain experience and may negatively impact patients’ satisfaction with pain management due to unmet expectations.


Background
Pain is a very common postoperative complication [1][2][3][4]. In Mulago National Referral Hospital (MNRH), 100% of patients that had undergone abdominal surgery had pain despite having received drugs to control their postoperative pain [5]. In a systematic review, factors affecting postoperative pain experience were categorised as surgical factors (type of surgery, duration of surgery), psychological factors (anxiety, psychological distress, and coping strategies) and preoperative pain. Sociodemographic factors like tribe, culture, age, gender, socio-economic status, occupation, educational level; if surgery is emergency or elective, type of injury and previous experience of pain have also been documented to affect the perception of pain [6,7].
The effects of pain go beyond physical delay of recovery to prolonged hospital stay, depression, failure to feed, chronic pain, posttraumatic stress disorder, poor social relations to mention a few. Reliable quanti cation of pain is necessary for effective pain treatment [8]. Recommended key principles of management include routine assessments of pain and of the effectiveness of interventions using the various available pain scales [9]. Another important criterion for assessing medical service quality is patient satisfaction. This is a conclusion reached by the patient after comparing their feelings during a medical service with their expectations. Patient and hospital factors play important roles with physician care, nursing care and personal concern being the most valued factors to patient satisfaction related to in-patient care [10].
High levels of postoperative pain are still reported even with availability of numerous drugs for postoperative pain management and explanations for this include insu cient education, poor pain assessment by attending clinicians and nurses, and inadequate sta ng [11]. Since pain is a multidimensional experience that encompasses physical, emotional, spiritual and behavioural aspects, a multidimensional approach in its management is therefore needed [12].
The American Society of Anaesthesiologists (ASA) emphasises preoperative anaesthesia review for all patients. One of the aims of this review is to provide the opportunity for explanation and discussion, and allaying fear and anxiety [13]. Several studies show that increased anxiety in the preoperative period is associated with increased postoperative pain [14][15][16][17]. Postoperative pain control therefore starts before surgery. Behavioural preparation of the individual is pertinent to adequately equip the patients in all possible ways of handling pain beforehand using preoperative information [12].
Preoperative education as a strategy to address said anxiety in the preoperative period is regarded to be an appropriate intervention to decrease postoperative pain and in uences patients' postoperative pain experience.
Patients who receive preoperative information about pain, experience less pain and require less analgesia [18]. On the contrary, some studies suggest that patient education preoperatively about pain sensitises them to experience more pain [19,20], while others may fail to understand leading to dissatisfaction with treatment and general care postoperatively [11,13].
In Uganda, there is no standardised pre-operative assessment protocols or information about use of counselling preoperatively about pain to help in guidance of its use in patient management. We sought to understand the role of preoperative pain information on the postoperative pain and patient satisfaction in our setting. For this single centre, we consecutively recruited all patients during the study period who were 18 years and above, scheduled for elective orthopaedic surgery, that consented to participate in the study. We excluded those with surgically unrelated chronic pain, bone cancer and those that were previously recruited but came back for resurgery for the same/different condition.

Methods
Randomization and concealment: Block randomization was used for this study with block size of 5 to ensure equal distribution of patients in each arm. A computer program was used to generate the randomization sequence of patient allocation to either the intervention or control arms by an independent statistician. Arm1 received speci c information about pain preoperatively (intervention) while Arm 2 did not receive any information (control). The study numbers were allocated sequentially following the aforementioned codes. The randomization code was sent to the principal investigator in an opaque carrier envelope by an independent statistician who was not part of the study. They were similar to computer generated number sequence, becoming the patients study number.
Blinding: The study was double-blind with the research assistants, anaesthesia providers and the statistician blinded to the assignment and the arms to which the patients belonged.

Protocol
All patients admitted for elective orthopaedic surgery, were expected to have a pre-operative visit by the anaesthetic provider on the day before surgery. The principal investigator recruited all the patients to ensure consistency.
Randomization was based on computer-generated codes.
To conceal allocation, sealed opaque envelopes were opened only shortly before administering the intervention.
After consent bedside, they were randomized. Demonstration of the Verbal Numerical Rating Scale (VNRS) and how to indicate the level of pain they experienced was done. The intervention arm privately received speci c preoperative information about pain from the principal investigator in addition to the preoperative assessment. A trained assistant assessed the pain scores postoperatively at 0, 12, 24, 48hours or till discharge if less than 48hours.
We used a pretested interviewer administered questionnaire for both the intervention and the control arm. The questionnaire included the patient demographics, vital baseline clinical characteristics, intra operative and postoperative parameters at 0, 12, 24 and 48hours. The patient satisfaction with pain management were also recorded. This was adapted from an unpublished study by Kimenye et al in Mulago National Referral Hospital and adjusted to suit our study [21].
When a patient was found with postoperative pain, the doctor/nurse on duty was informed so as to manage it according to their discretion. All lled data collection tools were checked for completion on a daily basis. Data was entered into EPIDATA-Entry software.
The intervention: Speci c preoperative information about pain was given verbally following an order on the lea et.
This information involved the following: emphasis on patient's own role in pain management, bene ts of welltreated postoperative pain, role of physiotherapy, use of basic pain medication, disadvantages of poorly controlled pain, practical physical methods of pain management and other facts about postoperative pain. These are based on studies by Gammon et al and Louw et al. methods [22,23].

Measurements
Socio-demographic data was recorded as well as type of surgery, duration of surgery, type of anaesthesia, pain scores, pulse rate, analgesics given, patient satisfaction and anaesthesia provider.
We also assessed patient satisfaction with pain management which was a yes or no answer. Those that were not satis ed with the management were requested to give reasons.
Sample size calculation and statistical analysis Sample size calculations for our trial were based on the study of Sjöling et al [12]. Power analysis determined that a sample size of at least 165 subjects per arm would achieve 80% power to detect a difference in VNRS scores between the two arms, with a signi cance level α of 0.05.
Arms were primarily compared for balance in patients' demographic data, intra-operative characteristics and postoperative variables.
Data was analyzed using STATA version 12.0. Continuous variables were summarized using means, standard deviations, medians, and ranges. Categorical variables were summarized using frequencies, proportions, and percentages. Box and Whisker plots were drawn to also present the continuous variables. The differences between arms were regarded as being statistically signi cant if the P-value was less than 0.05.
To assess the effect of preoperative information about pain, the outcome was dichotomized as yes  and no (VNRS0-3). Bivariate analysis was performed for each of the independent variables to determine association with outcome. The association was assessed using logistic regression and its strength was summarized using odds ratios and 95% con dence intervals. Variables with a P-value of ≤ 0.2 at bivariate analysis were considered for multivariate model. Multivariate logistic regression was performed to determine how preoperative pain information as a main predictor is associated with the outcome. Interactions between the variables which remain in the model were assessed using the Chunk test followed by assessing for confounding using a difference of ≥ 10% between the crude and adjusted measure of effect (OR) for the variables that would have gone out at each step.

Results
A total of 400 patients were screened and 398 were enrolled for the study, 198 were enrolled to the intervention arm while 200 to the control arm, 170 were analysed in each arm as shown in the consort ow diagram (Figure 1).
The baseline patient characteristics in both arms were as shown in Table 1. The mean preoperative pain score of patients in the intervention arm was 3.52 SD (2.45) and 3.59 SD (2.63) in the control arm. The highest pain score was noted to be at 12 hours and the lowest at 0 hours in both arms. The median pain scores at 0, 12, 24hours had no statistically signi cant difference in both arms. At 48 hours, there was a statistically signi cant difference between medians of the intervention and control arms with P-value= 0.029 (Table   2).   Table 3).  The individuals in the two arms of the study had comparable demographics for age, preoperative analgesia, history of drug and alcohol abuse, and ASA classi cation. However, there were statistically signi cant differences in the education level of participants with people in the intervention arm more educated than those in the control arm. In a prospective study among general surgery patients, it was discovered that patients with lower level of education were prone to experiencing higher pain scores than the more educated and could be mainly due to the poor understanding of the preoperative information, the level of anxiety and depression caused by that and the suboptimal request and use of analgesia [24]. This could also contribute to skewing of our nal results in this study. Level of education has been also found to have an impact on patient satisfaction with the less educated being more satis ed [25]. At multivariate analysis however we did not realise any signi cant difference in effect of level of education on patient satisfaction and pain experience which is contrary to what is already know in high income countries. This could be attributed to the cultural and social setting in low income countries where healthcare is usually taken as a privilege by majority of patients.
Postoperative pain experience: Patients in both arms experienced pain the least immediately after surgery and it increased to highest recorded pain score at 12 hours in this study. This may be because in ammatory mediators have been found to be highest 6-8 hours post-operatively and re ects the acute phase response peak that occurs in the rst 24 hours following surgery [26,27].
Our study showed that there were no overall signi cant differences between the arms regarding the overall perception of pain at 0 and 24 hours. This nding is in agreement with two systematic reviews which both concluded that preoperative education for orthopaedic surgery has no statistically signi cant effect on postoperative pain experience [23,28]. This may also be due to the fact that the type of intraoperative and postoperative analgesia for the patients was not controlled for in our study and the use of the one-on-one method of educating the patients. A study comparing the effect of individual and group preoperative teaching on postoperative outcomes, showed group education to be just as effective as, and more e cient than individual education [29].
At 48hours post-surgery, the patients in the intervention arm had lower VNRS pain scores compared to the control arm and this was statistically signi cant. These ndings imply that postoperative pain experience improved progressively with time and was in uenced by the individual preoperative education. A similar study in Sweden noted that postoperative pain declined more rapidly for patients in the intervention arm [17]. Studies done in both high income and low income settings agree with our study ndings that preoperative patient education improves postoperative pain experience [17,30]. It may be concluded from the above published data that as pain due to actual injury to tissues reduces, the effect of preoperative counselling about pain has a more profound positive in uence on the postoperative pain experience.
According to a review article by Rawal, a pain score ranging from 4-10 on VNRS is considered to be inadequately treated pain [31]. In our study, 61% of all the patients experienced pain of four or more on the VNRS, a pattern similar to Pavlin et al in USA [32]. Our ndings are however lower than those from a study done in MNRH by Kiswezi et al whose nding was 100% postoperative pain after laparotomy [5]. The differences between the two studies is rooted in the type of surgeries considered (laparotomy Vs orthopaedic surgery) and methodology.
Long surgery time and major surgery were found to signi cantly in uence pain experience irrespective of the counselling about pain preoperatively. This is similar to what has been found in other studies that included duration of surgery and type of surgery as being signi cant determinants of the postoperative pain experience [33,34].
Patient satisfaction: In both arms of our study, there was no difference in patient satisfaction with pain management. This contrasts literature indicating that speci c preoperative information improves patient satisfaction [12,35]. In our study population, the outcomes of patient satisfaction maybe more related to the varied nursing care received [12,36]. Additionally, those in the intervention arm could have had raised expectations which were not met making them less satis ed than expected.
Provision of analgesia in our study was not signi cantly related to patient satisfaction and this was more pronounced in the control arm than the intervention arm. Equivalent studies showed that patient satisfaction was more related to the nursing care than actual analgesia provision. It was only related to analgesia provision as long as pain was well controlled [37,38]. Provision of analgesia in our study was left to the discretion of the clinical care team. A study in MNRH stressed challenges in pain management such as widely spaced analgesic prescriptions, irregularities in timing of analgesic doses, and sometimes unavailability of the prescribed analgesics [5]. The highlighted issues were still present at the time of our study and could have contributed to our ndings in relation to patient satisfaction.
This was a pragmatic randomized clinical trial with a large sample size to show the effect of this information. Our study was done at a national referral hospital which receives patients from all over the country making our ndings generalizable.
Limitations in our study included ascertainment bias and lack of control for analgesia regimen. Ascertainment bias in this study may have arisen from the study participants in the control arm being given additional preoperative information by the unknowing anaesthetic providers during pre-anaesthesia assessment as this was a double blind study. Analgesia regimens was not controlled for which could have affected the results.

Conclusion
Patients that received preoperative information about pain experienced lower and sharp declines of postoperative pain scores, but had a lower satisfaction than expected mainly due to unmet expectations with nursing care.
Therefore, the use of preoperative information is vital in pain management postoperatively for patients and should be used together with the other standard postoperative pain management protocols in order to have good outcomes.
We also recommend that it is vital to have nurses directly involved in educating patients while on ward about surgery and postoperative pain as satisfaction was found to be much more related to nursing care.
We recommend future studies looking at the effect of preoperative pain information on pain experience with established/similar analgesic regimes, nursing involvement and continued counselling postoperatively. Each participant provided written informed consent.

Consent for publication
Not applicable.
Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author on request.

Competing interest
There are no competing interests.

Funding
There was no external source of funding for the study.
Author's contributions: MO the principal investigator designed the research, sought ethical approval, trained the data collectors and data entrants and wrote the report. JM, EA, CL, AW and PM were co-investigators. They helped in designing the study and obtaining ethical approval and JM helped with randomisation, cleaning and analysing the data. CS helped with designing the protocol and writing the nal report. All the authors helped with writing the nal report.