Accurate assessment and management of pain after surgery are crucial for reducing patient morbidity and mortality.[5] Previous studies have analyzed postoperative pain score trends and opioid use trajectories among hospitalized pain management patients using k-means clustering and have shown promise for segmenting subgroups, which could subsequently aid in personalized pain management.[8–10] These findings align with those of our research, which focused on the necessity of sophisticated pain management.
Table 4 provides a detailed analysis of surgeries by type, revealing significant differences even within the same category. The proportion of cancer surgeries was notably higher in cluster 1, accounting for 41.3% of the cases. The age of patients undergoing cancer surgery was significantly higher than that of those undergoing other types of surgery (56.3 ± 14.3 years for cancer surgery, 24.4 ± 6.27 years for orthognathic surgery, and 40.9 ± 15.7 years for minor surgery; p < 0.001). This suggests that the statistically significant differences in age and surgical duration observed in Cluster 1 could be compared to Cluster 3, in which only 12.2% of surgeries were cancer-related, predominantly within 46.7% of simple mass excisions. Although the cancer surgeries included in the study were almost evenly distributed across the three clusters, examination of the detailed surgical procedures revealed distinct differences. The cancer surgeries in Cluster 1 showed a higher frequency of mass excision combined with neck dissection and reconstruction, whereas in Cluster 3, the surgeries were predominantly simple mass excisions. Thus, while both are classified as cancer surgeries, patients undergoing procedures involving neck dissection and reconstruction are approximately 50% more likely to fall into Cluster 1. Conversely, those who underwent only mass excision had a 55.3% likelihood of following the pain trajectory of Cluster 3.
In orthognathic surgeries across all clusters, the most common procedures involved osteotomies of the maxilla and mandible, followed by concurrently performed genioplasty. Specifically, the pain trajectory for surgeries involving osteotomies of the maxilla and mandible was most frequently associated with Cluster 2 (49.3% of cases) and least frequently with Cluster 1 (13.7% of cases). When only osteotomy of the maxilla or mandible was performed, the pain patterns were most likely to align with Cluster 3. Conversely, although one might expect the pain to worsen with the addition of genioplasty owing to the increased surgical field, the frequency of being categorized in Cluster 3 was higher than that in Cluster 2. However, from another perspective, among patients undergoing osteotomies of the maxilla and mandible, 13.7% fell into Cluster 1 for postoperative pain, whereas for those who also underwent genioplasty, the rate was 17.2%, which was approximately 3.5% higher. Further analysis and examination of surgical differences are necessary for future research to understand the reasons for this finding.
Among the minor surgeries, reconstructive surgery was the most common across all clusters, followed by dental surgery. Overall, 53.2% of the minor surgeries followed the pain trajectory of Cluster 3. Except for TMJ surgery, which mostly follows the pain trajectory of Cluster 2 (although the number of cases is too small to make generalizations), all other types of minor surgery predominantly show the pain trajectory of Cluster 3.
Owing to the higher frequencies of cancer surgery and orthognathic surgery compared to minor surgery, the extensive surgical field and consequent increase in incision areas and tissue inflammation likely contributed to the moderate-to-severe postoperative pain experiences observed, particularly in Cluster 1.[2, 11–13] These findings suggest that not only the category of surgical procedure but also the specific surgical details and extent should be considered when managing postoperative pain. This study provides insights into the patterns of postoperative pain complaints based on the surgical details.
The limitations of this study include its focus on hospitalized patients, which does not account for the growing number of outpatient surgeries, particularly minor dental procedures. Previous studies on outpatient versus inpatient surgeries for procedures such as hysterectomies, thyroidectomies, and spine surgeries have shown controversial results; however, no results for dental surgeries indicate that further research is necessary to understand outpatient dental surgeries.[14–16] Moreover, the intermittent nature of VAS assessments, which are conducted only at specific postoperative times, may overlook instances of breakthrough pain and additional analgesic requirements. While most surgeries use PCA, the lack of continuous pain recording makes it challenging to assess the influence of analgesic interventions on the VAS. Additionally, the administration of additional analgesics in the general ward was undocumented in the previously collected data. Furthermore, the preoperative assessments did not account for chronic pain. Prior use of pain medication and preoperative pain levels are known predictors of poor postoperative pain control.[5, 17, 18] Due to the retrospective nature of the study, there were missing data. Future prospective studies should consider these factors to obtain a more comprehensive understanding of postoperative pain management.
Despite these limitations, the study benefited from minimal follow-up loss due to hospitalization for > 36 hours postoperatively. Additionally, face-to-face assessments using the VAS allowed for reliable pain evaluation at predetermined times. Various types of surgeries have been evaluated, in contrast to other studies that primarily focused on specific types of surgeries, such as tooth extraction, and a small number of studies involving a variety of procedures have focused on the concepts of pain medication rather than detailed pain profiles.[19–23] However, what sets our study apart is the classification of patients based on changing patterns of postoperative pain and the subsequent analysis of surgical frequencies within each cluster, providing a novel perspective on postoperative pain. Furthermore, we meticulously analyzed the detailed surgical names according to the extent of the procedure, recognizing that merely categorizing surgeries based on their categories may not fully capture their complexity and invasiveness. By delving into the detailed surgical names and analyzing the extent of surgery, we aimed to understand the varying degrees of postoperative pain. While it is challenging to assess surgical difficulty and invasiveness based solely on surgical categories, our approach to understanding the scope of surgery and conducting an analysis accordingly aimed to minimize errors. The advantage of this analytical approach lies in highlighting the importance of sophisticated pain management techniques. Understanding how the degree of postoperative pain varies even within the same surgical category is crucial. As observed in our findings, patients undergoing similar oral cancer surgeries exhibited different postoperative pain patterns, depending on whether they underwent simple mass excision or more complex procedures, such as reconstruction or neck dissection. Recognizing these differences in postoperative pain patterns can aid clinicians in predicting postoperative pain, preemptively controlling pain, and explaining pain to patients. Furthermore, our institution's prominence in the field of oral and maxillofacial surgery, with the highest number of general anesthesia surgeries nationwide, ranging from simple surgical extractions to cancer surgeries, provides a unique opportunity to analyze postoperative pain profiles for various dental surgeries.
By addressing the limitations and controlling variables, future prospective studies in this field can offer valuable insights into postoperative pain management for patients undergoing oral and maxillofacial surgery and aid anesthesiologists and oral and maxillofacial surgeons in clinical decision-making processes.