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Assessment of acute postoperative pain management and associated factors after elective surgery among adult surgical patients: a prospective cross-sectional study

Kasahun, Habtamu G. MSc; Agizew, Tesfaye B. MSc; Temesgen, Mamaru M. MSc; Ashagrie, Henos E. MSc

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doi: 10.1097/SR9.0000000000000037
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Pain is defined as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage”1. Postoperative pain is usually related to tissue injury during surgical procedures like skin incision, tissue dissection, manipulation and traction. Such pain is usually acute and it serves an important factor to alert the body of potential or actual tissue injury and inflammatory responses2.

Acute postoperative pain has been one of the major challenges of modern medicine and globally 66.6% of patients admitted to hospitals still suffer from uncontrolled pain despite several numbers of study, better education of pain management, availability of new technologies for drug administration, potent analgesics, and clinical practice guidelines3–5.

Even though postoperative pain management (POPM) has been improved, available research continues to show that majority of patients report extreme pain. In the United States, Thailand and Sweden around 77%–83%, 80%, and 76% of patients report moderate to severe postoperative pain, respectively6–10, while in German only 29.5% of surgical patients experience moderate to severe pain11.

In Africa there are higher incidences of postoperative pain with poor POPM. In Nigeria and Kenya studies showed that 68.7% and 55.3% patient reported moderate to severe postoperative pain after surgery, respectively12,13. In Ethiopia at Jimma and Addis Ababa, moderate to severe postoperative pain was experienced in 88.2% and 49.7% of patients, respectively, and pain was inadequately treated in Jimma on 58.4% of those patients14,15. According to the previous study in Gondar about 57% and 78% of surgical patients experienced moderate to severe at 2 and 12 hour of surgery, respectively16.

Pain management is the relief of pain using different interventions including pharmacological and nonpharmacological approaches. Combination of systemic and regional nerve blocks provides better pain control4,17. Despite the advancement in pain management techniques, it has become a national and global challenge due to lack of integration of current knowledge and practice, which adversely affects patient outcomes, resulting in avoidable psychological and physical adverse events18.

There are evidences that ongoing training and education and the use of standardized, validated instruments to facilitate the regular evaluation and documentation of pain intensity by anesthesiologists and health care workers would result in optimum pain management19,20. Describing POPM and associated factors will help to identify pain incidence, risk factors, and postoperative pain assessment and management modalities in developing countries like Ethiopia. Therefore, we aimed to assess pain management and associated factors of acute postoperative pain after elective surgery among adult surgical patients at University of Gondar Comprehensive Specialized Hospital.


Study design, area, and period

University of Gondar Comprehensive Specialized Hospital (UGCSH) is located in Amhara National Regional state, Northwest Ethiopia. UGCSH operation theaters have undergone a wide variety of operations like general surgery, trauma and orthopedics, gynecology and obstetrics, pediatrics, neurosurgery, and others. The study was conducted in the UGCSH postanesthesia care unit and ward (surgical; orthopedic and gynecology) which all are the sites for elective surgery.

A prospective cross-sectional study was conducted from February, 2020 to May, 2020. All consecutively adult elective surgical patients aged 18 years and above who were operated during the study period at UGCSH were taken and the work has been reported in line with the STROCSS criteria21.

Study variables and data collection procedures

The dependent variable; postoperative pain.

Independent variables; socio-demographic variables perioperative factors (Fig. 1).

Figure 1:
Conceptual framework showing the relationship between postoperative pain and its associated factors at University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia, 2020 (n=190).

Sample size determination

There is no documented information on the incidence of postoperative pain after elective surgery in the study area. But a study done in Jimma, Ethiopia showed that the incidence of moderate to severe pain in 24 hours after elective surgery was 63%15. So based on this data sample size of this study was calculated by using a single population proportion formula.n=(Zα/2)2p(1p)d2where n=is the desired sample size; z=is standard normal distribution usually set as 1.96 [corresponds to 95% confidence level (CI) ]; p=population proportion with recent study; d=degree of accuracy desired [marginal error is 5% (0.05)].

So, if a 95% CI is desired to estimate the proportion within 5% margin of error, the minimum sample size was as follows. We have p=0.63, q=0.37 d=0.05, Z=1.96 (95% CI). Finally n=(Z α/2)2×p(1−p)/d2=(1.96)2(0.63×0.37)/(0.05)2, n=358.

Since the total number of major elective patients getting operation in our hospital annually is below 10,000, correction factor formula was used to get the exact sample size. Here at UGCSH, an average of 110 elective operations performed per month. By considering this data a total number of 330 patients might have been operated during the data collection periods. nF=n1+n/N, where: nF=adjusted sample size, n=initial sample size, and N=population size. So, nF=3581+358/330, nF=172. By considering 15% of nonresponse rate the total final sample size was 198.

Data collection procedure

Data were collected by using a structured questionnaire through direct observation, chart review, and interviews. The Pain Management Index (PMI), a validated tool used to measure the adequacy of pain management and Numerical Rating Scale (NRS): a validated pain assessment tool for postoperative pain assessment were used22,23.

Data processing and analysis procedures

Data was entered, coded, and cleaned using the Epi-data software and analyzed using SPSS version 2024,25. Model fitness was checked using a Hosmer-Lemeshow goodness-of-fitness test. Crude odds ratios with their 95% CI were estimated in the bivariable logistic regression analysis to assess the association between each independent variable and outcome variable. P-value <0.2 in the bivariable logistic regression was fitted into the multivariable logistic regression analysis. The strength of association was presented using adjusted odds ratio with 95% CI and P-value <0.05 was considered as statistically significant. Finally, data were presented using numbers, frequencies, tables, charts, and figures accordingly.


Demographic and postoperative pain incidence

During the study period a total of 198 patients were included. Eight patients were excluded from the analysis due to incomplete data and making the response rate of 96% (Table 1).

Table 1 - Socio-demographic characteristics of the study participants at University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia, 2020 (n=190).
Variable Frequency (n) Percentage
 Male 97 51.1
 Female 93 48.9
Age (y)
 18–38 83 43.7
 39–59 83 43.7
 60–80 24 12.6
 Orthodox 139 73.2
 Muslim 37 19.5
 Catholic 5 2.6
 Protestant 9 4.7
Educational status
 Illiterate 74 38.9
 Can read and write 22 11.6
 Primary school (1–8) 3 1.6
 Secondary school (9–12) 34 17.9
 College and above 57 30.0

According to the 24-hour postoperative pain score, 69.5% (95% CI: 63%–76%) experienced moderate to severe pain.

Postoperative pain assessment and management

The pain assessment scale was not used for 160 (84.2%) of study participants. The common problem to providing acute POPM were unavailability of potent analgesic in 105 (55.3%) followed by waiting physician prescription for strong opioid in 41 (21.6%), and fear of drugs side effect in 30 (15.7%). Regarding training on pain assessment and management, only 14 (7.4%) of the responsible physician took onsite training.

Adequacy of POPM

The pain management index scores indicated that 116 (61.1%) and 100 (52.6%) of patients were inadequately treated after 2 and 24 postoperative hours of surgery, respectively. When asked whether they needed more analgesics than received 117 (61.6%) of the patients replied yes. Even though patients analgesic request were not associated with moderate to severe postoperative pain 96 (50.5%) of patients requested analgesia with in the first 24 hours of surgery (Table 2).

Table 2 - Frequency and percentage of postoperative factors for acute postoperative pain after elective surgery at university of Gondar comprehensive specialized hospital, Northwest Ethiopia, 2020 (n=190).
Variable Frequency (n) Percentage
Adequacy of POPM at 2 h
 Adequate 74 38.9
 Inadequate 116 61.1
Adequacy of POPM at 24 h
 Adequate 90 47.4
 Inadequate 100 52.6
Postoperative pain assessment
 No 160 84.2
 Yes 30 15.8
Training on pain assessment and management
 No 176 92.6
 Yes 14 7.4
Limitations to providing POPM
 Unavailability of strong opioids 105 55.3
 Waiting physician for strong opioids prescription 41 21.6
 Fear of complications 30 15.7
 No standardized pain management protocol 14 7.4
The main reasons for not requesting analgesia
 Patients request analgesic 96 50.5
 Perceived physicians did what was important for me 16 8.4
 Pain would get better through time 34 17.9
 No idea about analgesia 18 9.5
 Asking was culturally unethical 13 6.8
 No pain to request analgesia 13 6.8
Information about your pain treatment options
 No 137 72.1
 Yes 53 27.9
Need of more pain treatment than you received
 Yes 117 61.6
 No 73 38.4
POPM indicates postoperative pain management.

Factors associated with postoperative pain after elective surgery

Ten variables which were significant on bivariable binary logistic regression analysis with P-value of <0.2 entered into multivariable binary logistic regression. However, on the multivariable binary logistic regression analysis, only type of surgery (general surgery), use of regional anesthesia for POPM, preoperative anxiety, history of previous surgery, length of incision, and duration of surgery were significantly associated (P<0.05) with moderate to severe postoperative pain after elective surgery.

Patients who have previous history of surgery were more likely to had moderate to severe pain when compared with no history of previous surgery [adjusted odds ratio (AOR): 3.425, CI: 1.176–9.975, P=0.024] (Table 3).

Table 3 - Bivariable and multivariable binary logistic regression showing factors associated with postoperative pain after elective surgery at University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia, 2020 (n=190).
Postoperative Pain Odds Ratio
Variables None to Mild (n) Moderate to Severe (n) Crude (95% CI) Adjusted (95% CI)
Expectations of postoperative pain
 Mild 50 74 1.00 1.00
 Moderate 6 44 4.955 (1.964–12.50)* 6.073 (0.860–18.353)
 Severe 2 14 4.730 (1.030–21.72)* 4.589 (0.744–28.296)
History of chronic pain
 No 44 86 1.00 1.00
 Yes 14 46 1.681 (0.835–3.385)* 2.360 (0.292–2.111)
Preoperative anxiety
 No 42 48 1.00 1.00
 Yes 16 84 4.594 (2.336–9.034)* 5.377 (2.226–12.988)**
History of previous surgery
 No 48 85 1.00 1.00
 Yes 10 47 2.654 (1.230–5.726)* 3.425 (1.176–9.975)**
Preoperative analgesics
 No 32 93 1.937 (1.023–3.669)* 1.306 (0.451–3.787)
 Yes 26 39 1.00 1.00
Type of surgery
 General surgery and urology 18 72 2.720 (1.217–6.078)* 3.602 (1.107–11.72)**
 Orthopedic 23 35 1.035 (0.460–2.327) 2.607 (0.591–11.498)
 Gynecologic 17 25 1.00 1.00
Nerve block for POPM
 No 21 67 1.816 (0.962–3.427)* 3.00 (1.206–7.465)**
 Yes 37 65 1.00 1.00
Length of incision (cm)
 <10 45 51 1.00 1.00
 ≥10 13 81 5.498 (2.704–11.17)* 5.431 (2.003–14.72)**
Duration of surgery (h)
 <3 43 75 1.00 1.00
 ≥3 15 57 2.179 (1.102–4.306)* 3.401 (1.271–9.103)**
*Significant in the bivariable logistic regression (P<0.2).
**Significant in the multivariable logistic regression (P<0.05).
CI indicates confidence interval; POPM, postoperative pain management.


In this study significant proportion of patients suffer moderate to severe postoperative pain. History of previous surgery, use of regional nerve block, length of incision ≥10 cm, long duration of surgery (≥3 h), type of surgery, and preoperative state-trait anxiety were significantly associated with moderate to severe postoperative pain.

The overall incidence of moderate to severe postoperative pain in the study area was 69.5% in the first 24 hours. This finding is comparable with studies done in Jimma (63%), Nigeria (68.7%), and Sweden (64%)12,14,26. However, this result was higher than studies done in the Netherlands (34%)27. This discrepancy might be due to lack of good clinical practice and potent analgesics. Similarly, a study conducted in Kenya moderate to severe postoperative pain shows (13%) in day case surgery13. This discrepancy might be due to the incidence of postoperative pain after day-case surgery was low as compared with inpatient surgeries.

In the current study, long duration of surgery >3 hours were an independent risk factor for moderate to severe postoperative pain (AOR: 3.401, CI: 1.271–9.103, P=0.015) than from those patients with surgical duration <3 hour. Similarly, the study conducted in Addis Ababa, Korea, and Canada supports the finding in this study15,28,29.

Another independent predictor for moderate to severe postoperative pain was length of incision >10 cm (AOR: 5.431, CI: 2.003–14.721, P=0.001). This result was similar to the pervious study in similar setup which revealed that, surgical site incision length of >10 cm was an independent factor for moderate to severe postoperative pain16. Another study in the Netherland also revealed that large surgical site incision was found to be a predictive factor for moderate to severe postoperative pain30. This is due to increase length of surgical site incision led to increase inflammation and sensitization of the peripheral and central neurons which causes increased postoperative pain31.

In this study, participants having preoperative anxiety 5.377 times (AOR: 5.377, CI: 2.226–12.988, P=0.001) more likely to had moderate to severe pain than those who were not having state trait anxiety. This finding was supported by a study done in Brazil, the likelihood of having moderate to severe postoperative pain was 1.74 times (OR=1.74) than those who were not having anxiety at the preoperative period32. Similarly, a systematic review and meta-analysis done in Canada revealed that preoperative anxiety had strongly associated with moderate to severe postoperative pain33. This is due to preoperative anxious state has been supported as a factor in lowering pain threshold, assisting overestimation of postoperative pain intensity34.

Severe postoperative pain significantly associated with a history of previous surgery and this study showed that those participants who had a history of previous surgery were more likely to have moderate to severe postoperative pain than from those not having previous surgery (AOR: 3.425, CI: 1.176–9.975, P=0.024). Similarly, a study in the United States also showed a strong association between moderate to severe postoperative pain and history of previous surgery (AOR: 1.28, 95% CI: 1.05–1.57)35. Another study done in Canada also, revealed that strong association between previous history of surgery and severity of postoperative pain (P=0.03)29.

Patients who underwent general surgery and urology 3.602 times (AOR=3.602, CI: 1.107–11.727) more likely to report moderate to severe pain than patient who underwent gynecologic procedure. This finding was against the study in Tanzania in which orthopedic procedures were found to be associated with moderate to severe pain (AOR=3.456, P=0.05)36. The possible explanation for this variation was the majority of orthopedics cases in our study had regional anesthesia for their POPM. Similarly, a systematic review in Canada shows a strong correlation between the type of surgery and postoperative pain37.

In this study, patients who do not had regional anesthesia were 3 times (AOR: 3.00, CI: 1.206–7.465, P=018) more likely to have moderate to severe pain than patients with regional anesthesia. A study in New York suggest that regional nerve block results in better analgesic and functional outcomes than conventional parenteral and oral analgesic therapy and had significantly less pain than controls (AOR: 3.5, 95% CI: 2.8–4.3 vs. AOR: 5.3, 95% CI: 4.6–6.0)38.

This study also revealed that, about 84.2% of patients have not been assessed by physician for the pain and only 29.7% of patients had received information about their pain treatment options. In contradict to this, a Cohort Study in Spain showed that pain assessment was obtained from 83.1% of the patients and 63.3% of patients had received information about pain treatment options. The possible explanation might be pain assessment is not routinely practiced in the study area as other vital sign. Regular assessment of pain would have increased chance of adequacy of POPM8.

This findings on the adequacy of POPM, about 61.5% and 52.6% of participants were inadequately treated at 2 and 24 hours of surgery, respectively; which is similar to study done in China which showed that about 60.2% of patients were inadequately treated for pain39.

Conclusion and recommendation

The present study found that significant proportion of patients suffer moderate to severe postoperative pain and demonstrates that majority of patients were inadequately treated at 24 hours of surgery. History of previous surgery, use of regional nerve block, length of incision ≥10 cm, long duration of surgery (≥3 h), type of surgery, and preoperative state-trait anxiety were significantly associated with moderate to severe postoperative pain. Therefore, the surgical team need to prepare and distribute a standard pain assessment scale as other vital sign sheets and need to take a plan of action to reduce the magnitude of the problem by addressing the risk factors.

Limitation of the study

The heterogynous surgical specialty (general surgery and urology, orthopedic, and gynecology), they were not equally represented and the sample size were not adequate because of decreased flow in elective cases due to COVID-19.

Ethical approval and consent to participate

This study was approved by the ethical review bord of School of Medicine, College of Medicine and Health Sciences with reference number of (1937/03/2020). Permission also received from medical director of the hospital before the commencement of the study. Data was collected from chart and log book clinical.

Sources of funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. At the time of data acquisition, the authors were employed at University of Gondar, Northwest Ethiopia, where the study was conducted.

Author contribution

This work was carried out in collaboration among all authors. H.G.K. contributed to the conception and design of the study, acquired, analyzed, and interpreted the data drafted and revised the manuscript. T.B.A., M.M.T., and H.E.A. participate in reviewing the design and methods of data collection, interpretation, and preparation of the manuscript. All authors participate in preparation and critical review of the manuscripts. In addition, all authors read and approved the manuscript.

Conflicts of interest disclosure

The authors declare that they have no financial conflict of interest with regard to the content of this report.

Research registration unique identifying number (UIN)





The authors would like to acknowledge the surgical department, School of medicine, College of Medicine and Health Science for supporting to conduct this research and also our appreciation goes to the data collectors, colleagues and staffs.


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Adequacy; Elective surgery; Factor; Incidence; Analgesia; Postoperative pain

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