Effect of Preoperative Pain Catastrophizing on Postpartum Depression and Chronic Postsurgical Pain After Cesarean Section: A Prospective Cohort Study

Background

Chronic Postsurgical Pain (CPSP) and Postpartum Depression (PPD) After Cesarean Section

Cesarean section (CS) is the most commonly performed surgical procedure worldwide, and its global prevalence continues to rise. The World Health Organization (WHO) estimates that the global CS rate will increase from the current 21.1% to 28.5% by 2030, reaching approximately 38 million cesarean births annually.¹ With changes in birth policies, the CS rate in China has already exceeded 40%.² Postoperative pain is a major concern for women undergoing CS. Poorly managed pain following the procedure adversely affects recovery, hindering mobility, limiting the ability to care for a newborn, and prolonging hospital stays.³ Additionally, inadequately controlled acute pain is a well-established risk factor for CPSP.⁴ The International Association for the Study of Pain defines CPSP as a pain that develops or intensifies after a surgical procedure, persists for at least 3 months, and is localized to the surgical area.⁵ The incidence of CPSP following surgical operations ranges from 3.3% to 46.1%, representing a significant clinical problem due to its negative impact on quality of life.^6,7 Despite the high frequency of CPSP, chronic pain after CS has not been well-studied. The vast number of CS performed worldwide suggests that CPSP will become an increasing public health concern. Thus, improved strategies for managing CPSP following CS could greatly benefit the lives of many women.

PPD is one of the most common psychiatric disorders of the perinatal period and one of the most important complications of CS. PPD has a global prevalence rate of 17.22%, with the highest risk of onset occurring within the first 3 months postpartum.⁸ PPD not only affects maternal physical and mental health but also reduces lactation, affects the mother-child relationship, and has long-term implications for the child’s health.⁹ Given these consequences, it is crucial to identify factors that contribute to PPD symptoms in new mothers.

Effect of Preoperative Pain Catastrophizing on CPSP

Pain catastrophizing is a cognitive pattern characterized by negative thoughts and feelings about pain, including magnification, rumination, and helplessness.¹⁰ Pain catastrophizing has been shown to prolong postoperative opioid use and exacerbate postoperative acute pain.¹¹ It has been shown to be associated with increased acute pain after CS in a prospective cohort study and worse outcomes in analgesic effect and satisfaction.¹² However, the relationship between pain catastrophizing and chronic pain after CS remains unclear. A meta-analysis of 41 studies demonstrated a significant association between pain catastrophizing and CPSP after surgery.¹³ Therefore, exploring the relationship between pain catastrophizing and CPSP may be of great significance for pain management after CS.

Effect of Preoperative Pain Catastrophizing on PPD

CPSP, pain catastrophizing, and mental health disorders such as depression frequently co-occur and are challenging to manage. Evidence suggests that pain catastrophizing may contribute to depressive symptoms, potentially mediating the relationship between chronic pain and depression.¹⁴ In a longitudinal study of chronic pain, pain intensity or catastrophizing change, depressive symptoms change in the same direction.¹⁵ Patients with a high level of pain catastrophizing are prone to a sense of helplessness in the face of pain and amplify the negative emotions brought about by pain. PPD is a significant health concern for postpartum women, with a prevalence of 23.5% among healthy mothers in a recent study.¹⁶ The risk is higher in women who undergo CS due to surgical trauma and related complications.¹⁷ Exploring the influence of preoperative pain catastrophizing on PPD is therefore of considerable clinical importance.

We investigated the effects of preoperative pain catastrophizing on the incidence of CPSP and PPD in Chinese women undergoing CS. Preoperative pain catastrophizing were assessed 2 hours before surgery, and data such as intraoperative bleeding, incision length, and postoperative pain control were collected. CPSP and PPD were assessed at 3 and 6 months, respectively, and their associations with preoperative pain catastrophizing were analyzed.

Methods

Setting and Participants

A prospective cohort study was conducted on a consecutive sample of patients who underwent CS and were discharged from Mianyang Central Hospital, School of Medicine, University of Electronic Science and Technology of China, between January 15th, 2023, and August 15th, 2023. Written informed consent was obtained from all participants prior to inclusion in the study. The study was conducted in accordance with the Declaration of Helsinki and the World Medical Association and was approved by the Ethics Committee of Mianyang Hospital Affiliated with the University of Electronic Science and Technology of China (Reference Number: S20230369-01) on January 11th, 2023. The aim was to analyze the effects of preoperative pain catastrophizing on CPSP and PPD in CS. The inclusion criteria were: (I) age > 18 years, (II) gestational age of 37–42 weeks, and (III) ability to provide informed consent. Participants with chronic pain during pregnancy, mental disorders, serious obstetric complications, other underlying medical conditions or refusal for participation were excluded.

Instruments

Sociodemographic Information Questionnaire

Demographic data collected included age, BMI, repeat cesarean delivery, emergency surgery, anesthesia method, ASA classification, length of incision, duration of surgery, intraoperative hemorrhage, birth weight, complications, inadequate analgesia after surgery, CPSP at 3,6 and 12 months, and PPD at 3, 6 and 12 months.

Pain Catastrophizing Scale

The Pain Catastrophizing Scale (PCS) was used to evaluate rumination, magnification, and pessimism. The PCS is a reliable and valid tool for pain and psychometric studies.¹⁸ Each item is scored on a scale of 0 (not at all) to 4 (all the time), yielding a total score range of 0 to 52, with higher scores indicating greater levels of pain catastrophizing. In the current sample, the PCS demonstrated’ high internal consistency (Cronbach’s alpha=0.91). A total PCS score of 30 was considered clinically significant for pain catastrophizing.¹⁹

Chronic Postsurgical Pain

Pain severity was measured using a Numeric Rating Scale (NRS), ranging from 0 to 10, where 0 indicates no pain and 10 indicates the maximum imaginable pain.¹⁷ CPSP was defined as pain developing after surgery in or near the surgical site and persisting for≥3 months, with an NRS score of 1 or higher at rest and/or during movement.²⁰

Postpartum Depression

The Edinburgh Postnatal Depression Scale (EPDS) was used to assess PPD. This instrument consists of ten multiple-choice questions (with four options). The options for each item were scored from 0 to 3 based on symptom severity. The range of scores was 0‒30. Higher scores indicate a greater number of depressive symptoms. Good internal consistency for the EPDS was observed in the current sample (Cronbach’s alpha=0.89). PPD symptoms were measured at 3,6 and 12 months postpartum, with scores > 13 indicating the presence of depressive symptoms.²¹

Data Collection

Data were collected by personnel trained in standardized protocols. The structured questionnaire, including general demographic information and PCS, was administered during the preoperative anesthesia assessment within 2 hours before surgery. The purpose of the study was explained to the patients and informed consent was obtained. Participants willing to participate in the survey completed the questionnaire independently, under the unified guidance of the researchers. Anesthesia methods, ASA, incision length, operation duration, intraoperative bleeding, birth weight, and complications were collected from electronic medical records before discharge. Insufficient analgesia was recorded if the NRS score exceeded 3 points at 24/48 hours after surgery.

Two investigators, who were trained in the use of standardized telephone interviews, conducted follow-up assessments at 3,6 and 12 months postoperatively. Three months after surgery, patients were contacted by telephone to assess the presence of pain. Patients reporting pain at 3 months were followed up for 6 and 12 months. The patients were blinded to their perioperative care to avoid potential bias. After confirming no evidence of disseminated or recurrent disease, each patient was asked about any pain experienced at or near the surgical site and whether this pain developed specifically after the surgery. Patients who answered “no” to these questions did not proceed with further questions, while those who answered “yes” completed the interview questionnaire.

Data Analysis

Data were coded, entered, and analyzed using IBM SPSS Statistics for Windows, version 26 (IBM Corp). Continuous variables were expressed as mean±standard deviation(SD) or as median and interquartile range. Categorical variables were presented as numbers and percentages. Univariate analysis was performed between the CPSP and non-CPSP groups and the EPDS and non-EPDS groups. Continuous variables were analyzed using the Mann–Whitney U-test or the independent samples t-test, depending on normality. The chi-square test was used to compare categorical variables. Spearman correlation analysis was used to examine the relationships between PCS, CPSP, and PPD at 3 and 6 months after surgery. Variables with P< 0.05 were entered into multivariate stepwise backward logistic regression to identify predictors of CPSP and PPD. Odds ratio(OR) with corresponding 95% confidence interval(CI) were calculated for each variable to assess the variable’s impact on CPSP prediction. The goodness-of-fit of the logistic regression model was evaluated using the Hosmer-Lemeshow test. Statistical significance was set at P < 0.05.

Results

A total of 706 patients were recruited in this study. Twelve declined to participate, and 14 were excluded for the following reasons: no pain during the CS (n=3), severe complications (n=5), and being transferred to the intensive care unit (n=6). Among the remaining 680 patients, 13 dropped out during in-hospital follow-up, 1 was re-hospitalization and 8 were lost to follow-up during the telephone interviews conducted after surgery. This left data from 658 patients for analysis. A flowchart illustrating the patient inclusion process is provided in Figure 1.

Figure 1 Patient enrollment flow chart.

Prevalence and Characteristics of CPSP and PPD

Data from 658 participants were analyzed, representing a response rate of 93.2% (658/706). The average age of the participants was 31.51±4.31 years. More than half of the participants had a BMI within the acceptable range of 18.5 to 28 (53.3%). Most underwent primary cesarean delivery (74.5%), emergency surgery (96.7%), intravertebral anesthesia (92.2%), and were classified as ASA III (92.1%).

In this cohort, 35.6% (234/658) reported PCS before surgery, 18.8% (124/658) reported CPSP at 3 months, 9.3% (61/658) at 6 months and 3.5% (23/658) at 12 months after surgery. The incidence of PPD at 3, 6 and 12 months was 14.0% (92/658), 6.8% (45/658) and 5.9% (39/658), respectively. Details of incision length, duration of surgery, intraoperative hemorrhage, birth weight, complications, and inadequate postoperative analgesia in the parturient women are summarized in Table 1.

Table 1 Demographic and Clinical Information of the Respondents (n=658)

Statistical analysis showed significant differences between the CPSP and non-CPSP groups and between the PPD and non-PPD groups at 3 months post-surgery in variables such as BMI, repeat cesarean delivery, length of incision, intraoperative hemorrhage, inadequate analgesia after operation, and PCS (P<0.05) (Table 2). At 6 months after the surgery, there were statistically significant differences in BMI, Length of incision, Intraoperative hemorrhage, Inadequate analgesia within after operation and PCS between the CPSP and the non-CPSP group, as well as between the PPD and the non-PPD group (Table 3). Similar differences were observed at 12 months after surgery (Table 4).

Table 2 Demographic, Clinical,and Psychological Factors Associated with CPSP and EPDS at 3 Months After Cesarean Section (n=658)

Table 3 Demographic, Clinical,and Psychological Factors Associated with CPSP and EPDS at 6 Months After Cesarean Section (n=658)

Table 4 Demographic, Clinical,and Psychological Factors Associated with CPSP and EPDS at 12 Months After Cesarean Section (n=658)

Correlation Analysis of Preoperative Pain Catastrophizing with CPSP and PPD

Spearman correlation analysis revealed significant correlations between preoperative PCS and CPSP at 3, 6, 12months, PPD at 3 months after surgery (r=0.858, 0.165, 0.158 and 0.192 respectively; P<0.05). However, no significant correlation was observed between PCS and PPD at 6 and 12 months (r=0.058,0.038 respectively; P>0.05) (Table 5).

Table 5 Correlation Analysis of Preoperative Pain Catastrophization, Depression and Postoperative Chronic Pain(r)

Binary Logistic Regression Analysis of CPSP and PPD at 3 Months After CS

As Table 6 shows, after adjusting for covariates (BMI, repeat cesarean delivery, length of incision, intraoperative hemorrhage, birth weight, and inadequate analgesia within the postoperative period), the PCS before surgery was independently associated with CPSP and PPD at 3 months after CS. The two models showed good calibration by Hosmer-Lemeshow goodness of fit statistic with x²= 7.197, P = 0.409 (CPSP at 3 months) and x² = 0.238, P = 1.015 (EPDS at 3 months), respectively. This indicates that the models demonstrated moderate discriminatory power and good calibration.²²

Table 6 Binary Logistic Regression of the CPSP and EPDS in 3 Months Following Cesarean Section (n=658)

Binary Logistic Regression Analysis of CPSP and PPD at 6 and 12 Months After CS

Binary logistic regression of CPSP and EPDS at 6 months after surgery showed that PCS was not independently associated with CPSP(OR 0.645,95% CI 0.265–1.568)and EPDS(OR 0.531, 95% CI 0.738–1.131) at 6 months after surgery, after adjusting for BMI, length of incision, intraoperative hemorrhage, birth weight, inadequate analgesia within after surgery. The Hosmer-Lemeshow test showed x²= 11.286, P= 0.186(CPSP 6 months) and x²= 2.038, P = 0.980(EPDS 6 months) which were indicating that the models had a good goodness of fit (Table 7).The same result was observed 12 months after the surgery, as shown in Table 8.

Table 7 Binary Logistic Regression of the CPSP and EPDS in 6 Months Following Cesarean Section(n=658)

Table 8 Binary Logistic Regression of the CPSP and EPDS in 12 Months Following Cesarean Section (n=658)

Discussion

With the increasing number of CS performed worldwide, CPSP has emerged as a significant postpartum complication. Similar findings were reported by Jin et al, who noted CPSP incidences of 18.3% at 3 months and 11.3% at 6 months in a prospective study of 527 women undergoing CS.²³ Borges et al followed 426 women who had CS and showed a 25.5% incidence of CPSP at 90 days after surgery.²⁴ CS plays a great role in the management of dystocia, pregnancy complications, and reducing maternal and infant mortality. However, due to the large incision and postoperative uterine contraction, severe acute and even CPSP can occur after surgery. CPSP not only affects the early rehabilitation and quality of life of parturients but also reduces lactation and affects the relationship between mother and infant.^25,26 Therefore, any measure targeting chronic pain after CS is of interest.

Moreover, CPSP is often complicated with PPD. PPD is an important complication in the perinatal period, and it is more severe in CS than vaginal delivery.²⁷ A quantitative study conducted by Agarwal et al found a two-fold increase in PPD risk following CS.²⁸ Many patients with CPSP may experience depression, which may be due to elevated inflammatory factors, inducing oxidative stress responses that lead to depression.²⁹ CS can lead to a range of surgical complications, such as infection, postpartum hemorrhage, ureteral and bladder injury, chronic pelvic pain, and gastrointestinal dysfunction. Adverse effects, such as stress caused by traumatic surgical events, may increase the levels of certain inflammatory mediators, thereby increasing the probability of PPD. A meta-analysis of the correlation between CS and PPD showed that the incidence of PPD 3 months after CS was 13.2%.³⁰ In women who underwent CS for early-onset preeclampsia, the proportion was even as high as 20.9%.³¹ PPD is often complicated by CPSP, which not only affects the postoperative recovery of the mothers and reduces breastfeeding rate, but also affects the sleep and weight gain of the infants.^32,33 As CS rates continue to rise globally, addressing these complications is imperative to improve maternal and infant health outcomes.

Furthermore, our most important finding was that preoperative PCS was an independent risk factor for CPSP and PPD at 3 months after surgery. However, given that the data at 6 months after surgery were not statistically significant, respectively, further and longer follow-ups are required to validate these findings. PCS has been shown to be associated with acute postoperative pain, and can lead to insufficient analgesia and affect analgesic satisfaction.¹² Meanwhile, both PCS and acute postoperative pain predicted severe CPSP. The link between pain catastrophizing and CPSP has been demonstrated in total knee arthroplasty,^34,35 potentially mediated by elevated levels of inflammatory markers in patients with high pain catastrophizing.³⁶ In agreement with our findings, Terradus-Monllor et al found that the level of PCS significantly predicted CPSP at 3 months after surgery but was not significant at 6 months after surgery.³⁷ A longitudinal cohort study showed that oxidative stress may mediate the effect of preoperative psychological conditions such as PCS on CPSP 6 months after surgery, potentially offering insight into its mechanisms.²⁹ There is a strong correlation between pain catastrophizing and depression. A study of chronic pain in adolescents shows that depression plays a mediating role in pain catastrophizing, pain intensity, and functional disability.³⁸ Pain catastrophizing indirectly affects dysfunction and pain intensity through depressive symptoms. Zeng et al found that PCS was associated with increased postpartum EPDS scores in nulliparous women.³⁹ PCS tendencies are predictive of increased distress during labor. Similarly, pain severity has important associations with increased depressive symptoms in mothers and consequences for perinatal and infant outcomes. Considering the influence of PCS on CPSP and PPD, medical staff can implement a brief psychoeducation or cognitive behavioral therapy session in the preoperative period, conducting routine PCS screening to identify high-risk patients. Given the lack of statistical significance in multivariate data at 6 and 12 months, additional longitudinal studies with extended follow-up periods are necessary to explore the relationship between PCS, postoperative CPSP, and PPD.

Additionally, our study revealed statistically significant differences in BMI, repeat cesarean delivery, length of incision, intraoperative hemorrhage, and inadequate postoperative analgesia between the CPSP and non-CPSP groups and between the PPD and non-PPD groups at 3 months after surgery. For CS, higher BMI increases the risk of acute postoperative pain.⁴⁰ Obesity also complicates regional anesthesia and prolongs the decision time for emergency CS,⁴¹ further heightening CPSP risk. Parturients undergoing repeated CS, being more familiar with the delivery process, may adapt better to labor and experience reduced stress response, potentially lowering their risk of CPSP and PPD.⁴² Longer incision lengths are associated with extended repair time, which may be accompanied by longer postoperative pain and affect postpartum psychological state. Meanwhile, intraoperative hemorrhage was associated with postoperative fatigue, as well as with postoperative EPDS score, which may influence postoperative chronic pain.⁴³ Inadequate postoperative analgesia implies inadequate postoperative acute pain control, which increases the risk of postoperative CPSP and PPD.⁴⁴ The results appear to be similar at 6 and 12 months postpartum, although it is important to note that there was no significant difference in repeat cesarean delivery at 6 and 12 months between the CPSP and non-CPSP groups and between the PPD and non-PPD groups. Given the multifactorial nature of CPSP and PPD, future research should consider additional sociodemographic, surgical, and anesthetic factors to comprehensively explore influencing variables.

Limitations

The primary strength of this study was the follow-up data collected from 658 women who underwent CS, extending to 12 months after surgery. However, this study had some limitations. First, the study was conducted at a single tertiary hospital in western China, which may limit the generalizability of the findings. Second, data collection relied on self-reported measures, introducing potential recall and social desirability biases. Lastly, other potential confounding factors that could affect PPD and CPSP, such as socioeconomic status, spousal/partner support, stress related to infant care, and previous psychiatric history, were not evaluated.Future research needs to include more variables to eliminate possible confounding factors and establish the causal relationship between variables.

Conclusion

This study investigated the incidences of CPSP and PPD at 3,6 and 12 months after CS and analyzed differences between clinical groups. The most significant finding was that preoperative PCS was an independent risk factor for CPSP and PPD 3 months after surgery. However, given the lack of statistical significance at 6 and 12 months, additional longitudinal studies are required to explore the causal relationships between preoperative PCS, CPSP, and PPD in women undergoing CS.