The U.S. government has declared opioid misuse a national emergency.1 Multiple studies have reported on the relatively higher effect of this epidemic among non-Hispanic white communities.2–5 In fact, a recent population-based study using data from California's prescription drug monitoring program reported a nearly 300% difference in opioid prescription prevalence among individuals of different race–ethnicity.2 Adults from communities with a greater proportion of white individuals were significantly more likely to receive at least one opioid prescription than those from lower- proportion white communities.2 Furthermore, these prescription patterns mirrored the observed rates of opioid overdoses.2
The reasons underlying these disparities in opioid prescribing have not been fully explained. However, several studies demonstrate health care disparities in treatment of pain for individuals of minority race and ethnicity. In particular, minority individuals have been shown to receive less opioid treatment than non-Hispanic white individuals for similar levels of pain and similar conditions.6,7 For example, one study examining 36.5 million emergency department visits found that non-Hispanic black individuals were significantly less likely to receive an opioid prescription at discharge for “subjective” pain complaints (eg, back pain, abdominal pain) but not for “objective” pain complaints (eg, kidney stones, fractures).8 Such differential prescribing may underlie some of the demonstrated disparities in the present opioid epidemic.
Whether such racial and ethnic disparities in pain management exist in the postpartum setting remains unknown, although many other racial and ethnic disparities in obstetric health services have been demonstrated.9 We hypothesize that similar disparities in pain management may exist with regard to postpartum inpatient and outpatient pain management. Thus, our aim was to evaluate racial and ethnic differences in women's postpartum pain scores, inpatient opioid administration, and discharge opioid prescriptions in a large and diverse cohort.
We conducted a retrospective cohort study of women who were hospitalized for delivery at a single high-volume tertiary care center over a 1-year period from December 1, 2015, to November 30, 2016. Women were included in this analysis if they were 18 years of age or older; self-identified as non-Hispanic white, non-Hispanic black, or Hispanic; and did not have documented allergies to nonsteroidal antiinflammatory drugs or morphine. Women were excluded if they had explicit evidence of recent opioid use, defined as having received three or more prescriptions for an opioid in the year before delivery. Additionally, women were excluded if they carried a diagnosis of opioid use disorder or if they had a prescription for buprenorphine, methadone, or fentanyl within a year of hospitalization. Women in other racial or ethnic groups or who had unknown self-reported race–ethnicity were excluded. This group was excluded because the additional racial and ethnic subgroups were individually of small sample size, and analyzing them together was not conceptually logical. Finally, we excluded women if they received general anesthesia, were admitted to the intensive care unit, underwent hysterectomy, or had a postpartum admission exceeding 10 days, because these conditions represent rare events10 and may reasonably be expected to result in analgesic requirements.
Electronic medical records were queried for demographic, clinical, and pharmacy data. Billing records, including International Classification of Diseases 9th and 10th Revision codes, were used to corroborate documented diagnoses of postpartum complications, substance use disorder, and psychiatric comorbidities. Pharmacy records were used to determine the amount of oral opioids administered during the inpatient postpartum hospitalization. This amount was standardized for differing postpartum lengths of stay by dividing the total amount of opioids used by days of hospital admission calculated to the closest hour. The details of all oral opioids were abstracted, including the type of opioid as well as the strength and number of tablets. All opioids were converted to oral morphine milligram equivalents (MMEs) to allow for comparison across types of opioids.11 Parenteral opioids were not included to decrease the likelihood of including acute immediate postdelivery analgesia needs, because it is exceedingly rare at our institution to use parenteral opioids outside of the immediate perioperative period. Whether an opioid prescription was provided at discharge was also abstracted from medical and pharmacy records.
At this academic tertiary medical center, more than 200 prescribers care for patients. Health care providers include resident and Fellow physicians training in obstetrics and gynecology, emergency medicine specialists, midwives, advanced nurse practitioners, and both privately and university-employed attending physicians. The patient's obstetric team is primarily responsible for managing postpartum pain. At the time of the study, there were no standard order sets for pain medicine prescriptions at the time of hospital discharge and no existing hospital guidelines about postpartum opioid prescriptions for either inpatient or outpatient use.
Three outcomes were evaluated for this analysis: 1) patient-reported postpartum pain score at discharge (dichotomized less than 5 or 5 or higher on a 0–10 scale), 2) inpatient oral opioid dosing during postpartum hospitalization (reported as mean MMEs/postpartum day), and 3) receipt of an opioid prescription at discharge.
Pain scores are assessed and recorded by nurses at scheduled intervals of 8 hours, before pain medications are received, and on discharge; women are asked to report their current perception of pain, with 0 equating no pain and 10 equating the worst pain imaginable. To assess perceived pain by race–ethnicity, we compared women who reported a pain score of less than 5 out of 10 with those who reported a pain score of 5 out of 10 or higher (representing moderate to severe pain12) at the time of discharge. Pain scores were dichotomized at this point, because a score of 5 or higher generally represents pain requiring analgesia for treatment.
Patient demographic and clinical characteristics were compared across racial and ethnic groups using χ2 and analysis of variance tests as appropriate. The associations of patient-reported postpartum pain score at discharge, inpatient opioid dosing during postpartum hospitalization, and receipt of opioid prescription at discharge with maternal race–ethnicity were assessed using multivariable regression models with random effects to account for clustering by discharge provider. Covariates in these models were those characteristics that were found to be significantly different (P<.05) by race–ethnicity on bivariable analyses. Multivariable models compared non-Hispanic black and Hispanic women with non-Hispanic white women. To evaluate whether any observed disparity differed according to route of delivery, interaction terms between each race–ethnicity category and vaginal delivery were entered into the multivariable regression and retained if they were significant, with the plan to perform additional stratified analyses by route of delivery for those outcomes. Finally, a sensitivity analysis was conducted in which women of different race and ethnicity were matched using propensity scores. All analyses were conducted using Stata 15. The Northwestern University Institutional Review Board approved this study.
A total of 9,900 women were eligible for analysis. The majority (68.4%) identified as non-Hispanic white, 21.0% as Hispanic, and 10.6% as non-Hispanic black (Fig. 1). The population was approximately half (48.3%) nulliparous, and the majority delivered vaginally (73.4%). Non-Hispanic white women were significantly older and had lower body mass indexes (BMIs) and were significantly more likely to be married, nulliparous, have private insurance, smoke tobacco, and have a history of depression or anxiety compared with Hispanic and non-Hispanic black patients. Non-Hispanic white women were less likely to have a history of nonopioid substance use disorder (Table 1). Non-Hispanic white women were also less likely to have had a prior cesarean delivery (P<.001).
On bivariable analysis, non-Hispanic white women were significantly less likely to report a pain score at discharge of 5 or higher (4.2%) than both Hispanic (7.7%) and non-Hispanic black (11.8%) women (P<.001). Yet non-Hispanic white women received significantly greater MMEs/d as inpatients (median 24.8, interquartile range 12.2–39.6) than Hispanic (median 19.4, interquartile range 8.7–32.7) and non-Hispanic black (median 23.5, interquartile range 11.0–36.1) women (P<.001). Non-Hispanic white women were also more likely to receive an opioid prescription at discharge (46.8%) than Hispanic (38.9%) and non-Hispanic black (45.3%) women (P<.001) (Table 2).
On multivariable analyses, the majority of significant associations from bivariable analysis remained significant (Table 3). Specifically, after we adjusted for age, marital status, nulliparity, gestational age, BMI, public insurance, tobacco use, anxiety, depression, substance use, mode of delivery, and prior cesarean delivery, Hispanic women (compared with non-Hispanic white women) had significantly greater odds of reporting a pain score of 5 or higher (adjusted odds ratio [aOR] 1.61, 95% 1.26–2.06) but received significantly fewer adjusted inpatient MMEs/d (adjusted β −5.03, 95% CI −6.91 to −3.15) and had significantly lower odds of receiving an opioid prescription at discharge (aOR 0.80, 95% CI 0.67–0.96). Similarly, non-Hispanic black women had significantly greater odds of reporting a pain score of 5 or higher (aOR 2.18, 95% 1.63–2.91) but received significantly fewer adjusted inpatient MMEs/d (adjusted β −3.54, 95% CI −5.88 to −1.20) and had significantly lower odds of receiving an opioid prescription at discharge (aOR 0.78, 95% CI 0.62–0.98). No interaction terms between race–ethnicity and route of delivery were significant, indicating that the observed disparities did not differ according to route of delivery.
In the propensity score–matched cohort analysis, there were no significant differences in matched patient characteristics that persisted after nearest neighbor matching (Table 4). In the propensity score analysis, findings were overall similar to the primary analysis. Hispanic women were significantly more likely than non-Hispanic white women to report pain scores of 5 or higher (OR 1.60, 95% CI 1.23–2.09), received significantly fewer adjusted inpatient MMEs/d (β −4.74, 95% CI −6.58 to −2.91), and were significantly less likely to receive an opioid prescription at discharge (OR 0.72, 95% CI 0.62–0.84). Non-Hispanic black women were significantly more likely than non-Hispanic white women to report pain scores of 5 or higher (OR 2.94, 95% CI 2.06–4.09) and were significantly less likely to receive an opioid prescription at discharge (OR 0.81, 95% CI −0.66 to 0.99). The difference in inpatient MMEs/d between non-Hispanic white and non-Hispanic black women no longer reached statistical significance.
In this study, we have demonstrated that Hispanic and non-Hispanic black women experience disparities in pain management in the postpartum setting that cannot be explained by less perceived pain. Even after we adjusted for potentially confounding covariates, both non-Hispanic black and Hispanic women were significantly more likely than non-Hispanic white women to report a pain score of at least 5. Despite this, Hispanic women received significantly fewer inpatient MMEs/d. Hispanic and non-Hispanic black women also had lower odds of receiving an opioid prescription on discharge compared with non-Hispanic white women. Although the significant odds ratios found lie within the zone of potential bias,13 these findings remain notable. Although the absolute difference in inpatient MMEs/d and rates of opioid prescriptions at discharge between non-Hispanic white and non-Hispanic black or Hispanic patients is small, this remains clinically significant in context; one may reasonably expect that groups reporting a greater amount of pain would not only receive equal amounts of pain management in the form of equal inpatient MMEs/d and rates of opioids prescriptions at discharge, but would receive an even greater amount of pain management, thus making these results especially poignant.
Racial and ethnic disparities in health care delivery and outcomes have been extensively documented in the literature.9 These disparities have extended to pain management, with racial and ethnic minority nonpregnant individuals having increased risk of less aggressive analgesia treatment. One retrospective study of data from more than 6,700 emergency department visits shows that non-Hispanic black patients were 22–40% less likely to receive analgesia for moderate to severe pain than non-Hispanic white patients.6 Another recent study, which examined disparities in the management of pain among more than 7,000 individuals in the outpatient setting, shows that non-Hispanic black and Hispanic individuals were significantly less likely to be prescribed an opioid for management of abdominal pain (6.0% and 6.3% less likely, respectively) and back pain (7.1% and 14.8% less likely, respectively).7 Additionally, studies have shown that minority patients who present with migraines and long bone fractures receive less pain medication than non-Hispanic white patients. Although such disparities in pain control have been understudied in the obstetric setting, out data suggest that postpartum women experience similar care disparities.
Other racial and ethnic disparities in obstetric care have been well documented. For example, a study of more than 100,000 peripartum women across 25 hospitals in the United States demonstrates disparities in obstetric care. Specifically, non-Hispanic white women were more likely to undergo induction of labor and initiate immediate pushing during the second stage of labor and less likely to receive general anesthesia at the time of cesarean delivery.9 However, data are sparse with regard to whether such disparities in peripartum analgesia receipt in general, and opioid receipt more specifically, exist. One particular disparity that has been noted is with regard to neuraxial analgesia in labor; multiple studies have demonstrated that non-Hispanic white women receive this type of analgesia significantly more frequently than women of minority race–ethnicity.14–17 Based on our findings in this large cohort, this disparity in analgesia persists into the postpartum period. Despite non-Hispanic black and Hispanic women reporting significantly higher pain scores, they received significantly less opioids as inpatients and were significantly less likely to be prescribed an opioid as an outpatient when compared with non-Hispanic white women. It remains unclear, however, whether such findings are the result of differential prescribing by obstetricians, differential management of pain by bedside nurses, or differential patient requests for or acceptance of opioid analgesia. Additionally, our data do not allow for exploration of adequacy of pain management; therefore, for example, we cannot draw conclusions regarding whether minority women's pain was undertreated or non-Hispanic white women's’ pain was overtreated.
Our study has several strengths. Although the postpartum period is increasingly recognized as a potential source of first exposure to opioids, little is understood about equity in pain management in the postpartum period. Further, the analysis is based on information retrieved directly from a medical record with highly granular data that allowed for collection of detailed opioid use, pain score, and patient characteristics. However, results must be interpreted in light of some limitations. The study was limited to a single institution and may not be generalizable to care models in other settings. Additionally, this study is retrospective and thus susceptible to incomplete data and misclassification. Further, we are unable to explore potential etiologies for differential inpatient MME use or differential prescribing of opioids on discharge. Further work on patterns of analgesia request, comparisons with baseline pain scores, and other health services factors such as cultural differences and language barriers may address these potential inequities. Moreover, future work on whether standardized electronic medical order sets and opioid prescribing protocols work to overcome these disparities is essential.
In summary, we evaluated racial and ethnic differences in women's postpartum pain scores, inpatient opioid administration, and discharge opioid prescriptions. Hispanic and non-Hispanic black women experienced disparities in pain management in the postpartum setting that could not be explained by less perceived pain. These data suggest that more standardized approaches to postpartum pain management may encourage racial and ethnic equity in analgesia management.
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