Influence of Demographic Factors on Pain Perception and Postoperative Opioid Consumption

Research Article

Austin J Anesthesia and Analgesia. 2020; 8(3): 1093.

Influence of Demographic Factors on Pain Perception and Postoperative Opioid Consumption

Abad-Torrent A1*, de Miguel M1, Sanaú B2, Cortiella P1, Suescun MC1, Suárez-Edo E1

¹Department of Anesthesiology, Vall d’Hebron University Hospital, Barcelona, Spain

²Department of Research and Development, Quantium Medical - Mataró, Spain

*Corresponding author: Abad-Torrent A, Department of Anaesthesiology and Resuscitation, University Hospital Vall d’Hebron - Barcelona, Spain

Received: September 11, 2020; Accepted: October 19, 2020; Published: October 26, 2020


Purpose: The purpose of this study was to analyse the influence of demographic factors on pain perception and opioid consumption in patients undergoing robotic prostatectomy and laparoscopic hysterectomy.

Methods: A total of 93 patients were included in this observational, prospective study. A telephone interview was carried out after one month of the surgery. The patients were asked about demographic information, academic training, employment situation and the perception of their pain by assessing the Visual Analogue Scale (VAS) before and after the intervention. During their hospital stay, the total consumption of morphine and VAS were collected.

Results: There were no statistically significant differences in VAS scores on the first postsurgical day and one month after the operation by sex, origin and academic training. On multivariate logistic regression analysis, qualified work and inactive status were independent protective factors for moderate-severe postoperative pain on the first day after surgery. There was higher morphine consumption in men compared with women in the first four postoperative hours (mean difference: 0.029 mg/kg; 95% CI: 0.006 to 0.05).

Conclusion: Sex, race and academic formation did not influence the perception of the intensity of postoperative pain and the opioid consumption, except for the first 4 hours of the postoperative period, in which women required fewer doses of morphine than men. Qualified work and inactive status were independent protective factors for moderate-severe postoperative pain on the first day after surgery. Before surgery, inactive patients had higher VAS scores than retired and active workers.

Keywords: Postoperative Pain; Academic Formation; Sex; Race; Employment Situation; Morphine


VAS: Visual Analogue Scale; BMI: Body Mass Index; TCI: Target- Controlled Intravenous Infusion; EC: Effect-Site Concentration; TOF: Train Of Four; IV: Intravenous; PACU: Post-Anaesthesia Care Unit; PCA: Patient-Controlled Analgesia; IQR: Interquartile Range; OR: Odds Ratio; CI: Confidence Interval; SD: Standard Deviation


Pain is a subjective, unpleasant, multidimensional experience, which comprises different emotional components, whether affective or cognitive. Even today, patients and some professionals interpret it as an acceptable and expected experience during any surgery.

The interindividual variety of each patient in the perception of nociception makes the management of postoperative pain extraordinarily tricky in any of its scenarios. There is a high chance that the amount of opiates to achieve proper analgesia varies according to the patient, despite undergoing the same surgery. Pain sensibility is measured by sociocultural (family history, gender roles and stereotypes or socioeconomic level), psychological (anxiety, depression, fear, catastrophism and both cognitive and behaviour aspects) or biological (age, genetics, sex, race) factors. Thus, we should not only focus on the development of new drugs or delivery systems but the indicators involved in individualised nociception and personalised analgesic treatment as well [1,2].

The point of this study was to analyse the subjective pain perception and opioid consumption in patients undergoing prostatectomy and hysterectomy according to their sex, race, study level, and socioeconomic status. The telephonic interview conducted a month after the surgery was the method used to examine the demographic factors.

It was intended to raise information to treat postoperative pain not only pharmacologically but considering psychosocial aspects.

Materials and Methods

A prospective observational study was conducted at a singlecentre, including 106 adult patients, of both sexes, ASA physical status scores I-III, scheduled for robotic prostatectomy or nononcological laparoscopic hysterectomy under general anaesthesia. The Ethics Committee of Vall d’Hebron Hospital (Barcelona, Spain) and the Spanish Agency of Medicines and Sanitary Products (Code EudraCT 2016-002824-98. Protocol Code: ANE_HEPUNOX) approved this study. Informed consent was obtained from all patients. Exclusion criteria were obesity (Body Mass Index (BMI) >35 kg/m2 for women and >42 kg/m2 for man), anxiety-depressive disorder, chronic psychotropic or opiate treatment, pregnancy, alcohol abuse, documented allergy to the study analgesics, history of neurological disease or refusal to take part in the study. Anaesthesia was achieved in all patients with Target-Controlled Intravenous infusion (TCI) of Propofol and Remifentanil using the Orchestra® Primea system (Fresenius-Kabi). Remifentanil was diluted to a concentration of 50 μg/ml for an Effect-Site Concentration (EC) proposed by Minto and propofol 1% for an EC proposed by Schnider. Rocuronium was used as a muscle relaxant in bolus according to TOF control. The patients were premedicated with 2 mg of Midazolam IV. Intraoperatively, they were administered Paracetamol 1 g IV after the anaesthetic induction and Dexketoprofen 50 mg IV 20 minutes before the end of surgery.

On transfer to the Post-Anaesthesia Care Unit (PACU), the patient’s level of analgesia was measured on a Visual Analogue Scale (VAS) from 0 to 10 (0 = no pain; 1-3 = mild pain; 4-6 = moderate pain; 7-10 = severe pain). If the first VAS score was 3, the patient was given Metamizole 2 g IV if it persisted at a level equal to or greater than 3, the nurse administered intravenous Morphine boluses until a good level of analgesia was achieved without exceeding 10 mg of the total dose.

Afterwards, an intravenous PCA pump (patient-controlled analgesia) of Morphine was initiated for the treatment of pain during the first 12 hours after surgery. The infusion system CADD-Legacy® PCA Ambulatory Infusion Pump, Model 6300 was programmed to a concentration of 1 mg/ml, just in requested bolus, of 0.5 mg of Morphine with a closing time of 10 minutes and a maximum dose of 3 mg/h. Likewise, rescue analgesia was prescribed if the staff deemed it necessary or if the patient specifically requested pain medication. During that time, the nursing staff digitally registered the pain value with the VAS, the administered analgesic medication, the haemodynamic signs and possible adverse events. Later, the information of the PCA (intended and administered bolus and total morphine dose) was written down into the record sheet.

One month after surgery, all participants were asked to answer a telephone survey. It consisted of a set of questions about demographic information, academic training, employment status and perception of pain before and after the intervention. Pain intensity was assessed according to VAS from 0 to 10 (0 without pain and 10 with maximum pain). The primary outcome was to evaluate the relationship between demographic factors with postoperative pain.

Statistical analysis

Continuous data were expressed as mean (standard deviation), or median and Interquartile Range (IQR) as appropriate, and frequencies and percentages (%) for categorical data. To study the possible relationship between qualitative variables, the Pearson X2 test or Fisher’s exact test was used.

Student’s t-test or Mann–Whitney U test was employed as appropriate to analyse the relationship between a quantitative variable and a dichotomous qualitative test. One way ANOVA followed by a post hoc Bonferroni t-test was used to compare more than two means between groups for normally distributed continuous data.

For Continuous data which did not follow a normal distribution, the Kruskal-Walis test was applied to compare more than two means. A Friedman statistical test for repeated measures was employed to compare pain (VAS scores) at different times of study, and twosampled comparisons between the different times of study were evaluated using the Wilcoxon signed-rank test.

It was analysed the bivariate relationship between each factor and moderate-severe postoperative pain (VAS ≥ 4 at day one after surgery, and day 30 after surgery. The Odds Ratio (OR) and the 95% Confidence Interval (CI) for all exposure factors also were calculated. Subsequently, forward stepwise multivariable logistic regression was performed to identify independent risk factors for moderate-severe postoperative pain at day one after surgery, and day 30 after surgery. Candidate variables included: gender, age, BMI, origin, academic formation, employment situation and pre-operative pain. In all cases, a p-value less than 0.05 was considered statistically significant. Statistical analysis was performed using SPSS 20.0 statistical package (IBM Corp., Armonk, New York, USA).


A total of 106 patients were recruited. Four patients were excluded for being unable to contact by telephone and nine for presenting incomplete documentation. Finally, the population sample analysed was 93 patients (Figure 1).