Psychological heuristics of “peak-end rule” in labouring parturients: A prospective cross-sectional study

INTRODUCTION The peak–end rule is a psychological heuristic in which people judge an experience largely based on how they felt at its peak (i.e., its most intense point) and at its end, rather than the total sum or average of every moment of the experience.[1] The principle was pioneered by the psychologist Daniel Kahneman and his colleagues in 1993 by their study titled “When More Pain Is Preferred to Less: Adding a Better End”, and it then provided a groundbreaking evidence for the peak–end rule.[2,3] In medical procedures, it suggests that a patient may have better satisfaction when peaks and ends are better managed. Thus, the satisfaction levels of a remembered procedure can drastically influence medical future.[4] However, contrary to its envisioned and contemplated implications, especially in the branch of anaesthesiology, which is obsessed with pain relief, there is no literature till date evaluating its use in altering pain management strategies. Although we target a good pain relief during labour analgesia, significant breakthrough pain still occurs in almost 14–55% of patients.[4,5] Considering these facts, we decided to evaluate the data of parturients receiving epidural labour analgesia and hypothesised that the peak and end pain scores should have a correlation with the patient’s satisfaction rather than the average pain scores. METHODS The study was approved by our institutional ethics committee (vide approval number HFW (MC-II)B(12)ETHICS/2024/9321 dated 16/5/2024) and was registered with the Clinical Trials Registry-India (vide registration number CTRI/2024/09/074396). It was a prospective cross-sectional study to find the correlation between the patient’s satisfaction and the peak, mean, and end-stage pain intensity during labour. All patients were counselled for the ten-point visual analogue scale (VAS) for pain with 0 as no pain and 10 as worst unimaginable pain. The satisfaction scores were graded as 1 very satisfied and 5 very dissatisfied (Likert scale). Also, a written informed consent was taken from the participating patients. Epidural labour analgesia was administered in accordance with the departmental protocol wherein an initial bolus dose of 8 ml of 0.1% ropivacaine was given with fentanyl 2 μg/ml, followed by a patient control epidural analgesia regimen with basal infusion: 8 ml/h, a lockout interval of 10 min, and a demand bolus dose of 2 ml. The sample size was calculated using OpenEpi software. Considering a finite population size of 6000 deliveries (normal vaginal deliveries done in a year at our institute) with a frequency of cephalic presentation around 97%, a confidence interval of 95%, and a design effect of 1, the approximate sample size came out to be 44. A total of 50 primigravidae parturients with established labour, in the age group of 18–35 years with singleton pregnancies and cephalic presentation, with a gestational age of 37 weeks or more, scheduled for normal vaginal delivery, and without having any antenatal comorbidities were finally included in the study. Patients on entering active labour were monitored every 30 min and at the time of delivery for VAS scores. For each participant, the mean, highest, and end (of last 15 minutes before delivery) VAS scores were calculated. These values were then compared with the satisfaction scores documented 24 hours after delivery. The outcome assessor was blinded to the study hypothesis. RESULTS Out of a total of 50 patients, six underwent caesarean section; these were excluded, and 44 patients were finally analysed. The median pain scores at cervical dilatation