Racial Differences in Adherence to Prescribed Analgesia in Cancer Patients: An Integrated Review of Quantitative Research

From the University of Pennsylvania School of Nursing, Philadelphia, PA.

Abstract

• Background: Racial/ethnic disparities in analgesic treatment for pain have been widely documented in the United States. However, the connection between race/ethnicity and adherence to prescribed analgesics has not been described.
• Objectives: To review and synthesize quantitative research documenting racial/ethnic differences in adherence to prescribed analgesia in cancer patients.
• Methods: We performed a systematic search of quantitative, primary studies in Scopus, CINAHL, PubMed, Ovid, PsychInfo, and EMBASE. The title and abstract of each article was reviewed for relevance and whether inclusion criteria were met. Evidence was examined for relevant outcomes, data collection methods, variables studied in relation to adherence, and the magnitude of association between race/ethnicity and adherence.
• Results: Seven studies met inclusion criteria. Reported rates of adherence varied in studies among Hispanic/Latinos, African Americans, Asians, and whites based on variation in measurement tools, research questions, populations from which participants were recruited, and predictive variables analyzed. Most existing studies of analgesic adherence used self-report to measure adherence. Only 1 study used a validated, real-time electronic instrument to monitor prescribed opioid adherence and had a longitudinal study design.
• Conclusion: Limited research has examined relationships between adherence to prescribed analgesic regimens and racial disparities. Existing studies point to the clinical and socioeconomic factors that may interact with race/ethnicity in explaining analgesic and opioid adherence outcomes in cancer patients.

Key words: race, ethnicity, adherence, opiates, analgesics, pain management, cancer, pain treatment disparities.

The ongoing opioid epidemic and recent development of the Centers for Disease Control and Prevention (CDC) guidelines for chronic pain management have shaped a national conversation on opioid prescription and utilization [1]. The CDC delineates provider recommendations for opioid prescription. This focus on prescribed medication regimens is inadequate without an understanding of how patients take or adhere to prescribed medications. Cancer patients are a unique group. Moderate to severe pain in cancer patients is usually treated with opioids, and adherence to analgesia has been conceptualized a key mediator of cancer pain outcomes. For instance, a recent study found that patterns of analgesic adherence, specifically, inconsistent adherence to strong opioids (World Health Organization step 3), is one of the strongest predictors of health care utilization among outpatients with cancer pain [2]. Approximately 67% to 77% of cancer patients experience pain that requires management with analgesia [3], especially in the absence of access to nonpharmacologic pain treatments [2]. Thus, barriers in relation to adequate pain management can result in poor pain treatment outcomes and impaired quality of life for cancer patients.

Insufficient pain management has been found to have a negative impact on the quality of life and physical and mental functions of patients with cancer [4]. Patients who experience severe cancer pain are significantly more likely to experience multiple other symptoms such as depression, fatigue, and insomnia, resulting in diminished physical function [5], social role function [6], and greater out of pocket cost of managing pain and asso-ciated symptoms [7]. Minority populations, however, disproportionately carry the burden of undertreated pain [4,8–11,13–16]. Evidence suggests that blacks/African Americans are more likely to experience unrelieved cancer pain [4,8–11,13–16]. They are also less likely than their white counterparts to receive analgesic treatment for cancer pain [8–11,13,15,16]. Little is known, however, about racial disparities in relation to adherence to analgesia for cancer pain when providers prescribe analgesics.

The purpose of this paper is to review the published literature that has addressed the associations between disparities and adherence to analgesia among cancer patients. Evidence was examined for outcomes studied, data collection methods, variables studied in relation to adherence, and the magnitude of association based on race and adherence.

Methods

We performed a systematic search of studies published between 1990 and the present in Scopus, CINAHL, PubMed, Ovid, PsychInfo, and the EMBASE databases. The inclusion criteria consisted of published articles in the aforementioned databases that were (1) set in the United States, (2) primary studies, (3) employed quantitative design, (4) assessed adherence or compliance to analgesics or adequacy of pain management using the Pain Management Index (PMI), (5) sample was exclusively minority or may have had a comparative group. The title and abstract of each article in the the search results was reviewed for relevance to study aims and inclusion and exclusion criteria, and any duplicates were eliminated. A total of 6 studies were found using this method (Table 1), and an additional study was found in the reference list of 1 of these 6.

Results

The 7 included studies were observational in nature; 4 were cross-sectional [4,12,15,16], 2 were retrospective [3,14], and 1 was prospective and used objective measures of analgesic adherence [13] (Table 2).

Defining and Operationalizing Adherence

Meghani and Bruner [16] point out that analgesic adherence is a “heterogeneous construct that lends itself to varied results and interpretations depending on the measurements used or dimensions studied.” Adherence to analgesia was explicitly defined in all 7 studies (Table 3). One study reported an adherence rate that was the total dose over 24 hours divided by the dose prescribed then multiplied by 100 [4]. The total dose over 24 hours was used in another study but was converted to an equianalgesic calculation [12]. Another set of studies used a similar definition but specified percentages based on medication or type of prescription, such as an around-the-clock(ATC) regimen [13,15,16]. In 2 studies, adherence was measured based on chart review of yes/no questions posed about whether or not patients had taken medications as prescribed [3,15].

The measurements of adherence differed between studies. Four studies [4,12,14,16] used adherence as a primary outcome and the rest employed adherence as a facet of pain management [3,13,15]. The most frequent measure of adherence was self-report. The widely validated Morisky Medication Adherence Scale (MMAS) instrument was used in 3 of 7 studies [12,13,15]. Meghani and Bruner [15] utilized the modified MMAS plus a previously validated visual analog scale for doses of medication to assess adherence over week- and month-long intervals. One study used patient interviews to capture self-reporting of opioid prescription and opioid use. Additionally, the study used MMAS to further characterize the adherence measurements [12]. Using a more objective method, Meghani et al [13] employed a microprocessor in the medication cap to determine the percentage of the total number of prescribed doses that were actually taken [13]. The processor sensed when the bottle was open, which served as a proxy for taking medications at appropriate times.

Analgesic Adherence Rate

To report the analgesic adherence rates, 6 studies presented a percentage [3,4,12,13,15] and all but 1 highlighted the barriers associated with poor adherence [3,4,12,13,15,16].

The results of a pilot study exploring intentional and unintentional adherence revealed that 85.5% of patients took the prescribed medications in the previous week. Further analysis using visual analogue scale for dose adherence found that that 51% took up to 60% of the prescribed medications [15]. In an exclusively African-American sample, the adherence rate was reported as 46% [4]. Another study by Meghani et al compared adherence to prescribed ATC analgesics between African Americans and whites with cancer-related pain using an electronic monitoring system [13]. The overall adherence rate for African Americans was 53% and 74% for whites [13]. The authors concluded that there was a significant difference between the analgesic adherence rates between African Americans and whites in this study. On sub-analysis, analgesic adherence rates for African Americans were much lower for weak opioids (34%) and higher for long-acting opioids (63%).

In a study of individuals from an outpatient supportive care center with a majority white sample (74% Caucasian), overall 9.6% of patients deviated from the opioid regimen, while approximately 90% reported high adherence [12]. It is important to note that a convenience sample was used here. Of the total 19 patients that deviated from the regimen, 11 used less opioids than prescribed and 8 used higher doses. Upon analysis, the opioid deviation was more frequent in males and non-whites. However, statistical analyses of the magnitude of deviation from prescribed dose and non-white racial/ethnic background were not reported. Within the “non-whites” category, the race/ethnicity is defined as African American (16%, n = 32) and “other” (9%, n = 18). The authors contend that this strong adherence resulted from a strong understanding of the regimen as evidenced by a high agreement between the prescribed dose and the patient reported prescription [12]. Nguyen et al [12] argue that the literature shows that lower adherence rates for minority patients may be explained by the presence of comorbidities and lack of insurance.

Two other studies reported adherence rates for separate insurance cohorts [3,14]. The Medicaid cohort was younger and had a higher percentage of African-American individuals. However, in the self-pay/charity care group, the majority was Hispanic [3]. In the pilot study, the differences between the groups on adherence with prescribed medication regimens did not achieve statistical significance. The data were summarized to suggest that nonadherence was more likely in the self-pay/charity care group and more follow-up visits occurred after discharge [3]. During the larger retrospective study there was no difference in number of patients adhering to the regimen at each follow-up visit in each benefit group. The study concluded that the long-acting opiate adherence was influenced only by the benefits of use and that race/ethnicity was not a statistically significant predictor [14].