Our evidence synthesis shows that evidence to support any opioid reduction intervention for the tapering of opioids in people with chronic non-cancer pain is mixed and uncertain, with some interventions showing promise and others showing limited or no effect. However, with none of the studies done in the UK, the generalisability of our findings to NHS clinical practice is uncertain.
Our review findings highlight the complex nature of the tapering process with the potential for multiple interdependent, behavioural (individual/interpersonal level), structural (organisational level) and contextual (environmental) barriers to arise. To improve the chances of a successful outcome for patients with chronic non-cancer pain who are tapering opioids, there is a need for a whole systems approach to opioid tapering that is patient-centred and recognises that tapering is a dynamic, individualistic, intensive process. Our review findings also reinforce the perspective that the design and delivery of successful opioid-tapering initiatives require careful consideration of individual-level factors and that these individual-level factors have implications for interpersonal, organisational and environmental level approaches to opioid tapering.
Our review highlights the extent to which social inequalities (as defined by the PROGRESS-Plus framework) are considered in studies examining the effectiveness of, and access to, opioid-tapering interventions in adults with chronic non-cancer pain. The findings of this review demonstrate the potential for opioid-tapering interventions to widen inequalities in relation to both effectiveness and access and that inequalities may arise at various points along a tapering pathway, occurring at an individual, interpersonal, organisational or environmental level. Consequences of inequalities in access may include delays in seeking treatment due to anticipated stigma from providers, patient/provider-initiated discontinuation of health care, ultimately resulting in inequalities in effectiveness. It is imperative, therefore, that researchers and practitioners consider the impact on inequalities in the design and implementation of opioid-tapering initiatives.
Implications for research
Further research to identify the most effective method(s) of opioid withdrawal should be a priority. Data are needed from RCTs that consider the effect of theoretically grounded behaviour change interventions. Data should be collected from patients who have similar baseline characteristics. Treatment arms should be balanced in terms of use of other medications and multidisciplinary team input. Collected data should be used to explore how length of time taking opioids, baseline opioid dose and type of pain impact withdrawal programme effectiveness. The collection of long-term follow-up data would show whether any reduction in opioid use is sustained over time.
Our findings support the calls made by Mardian et al.131 for researchers, practitioners, patients and managers to work together to co-produce evidence on opioid-tapering initiatives to improve patient acceptability. Very few studies included in our review focused on patient acceptability or, indeed, the feasibility of specific opioid-tapering interventions. All long-term prescribing in the NHS is in primary care, so the lack of studies from a UK primary care perspective is striking and has important future research implications. The PSC report carried out on behalf of the MedSIP identified many examples of service activities across England, so activity is not lacking. There therefore needs to be evaluation to generate the evidence needed to understand and maximise the value of different approaches to tapering across the NHS. Given the importance placed on the existence of social support as a facilitator to achieving a successful taper, our review also echoes calls of previous review findings26 for more research on this factor.
In line with other systematic reviews that have investigated the impact of various interventions on inequalities,137,138 we echo calls for researchers to consider and report on the differential effects of opioid-tapering initiatives across wider PROGRESS-Plus characteristics, with sufficiently powered studies to detect significant differences should they exist. Furthermore, researchers should ensure their sampling strategies are inclusive and are representative of underserved populations (across the entire PROGRESS-Plus spectrum) that may be disadvantaged. The inclusion of qualitative studies examining barriers and facilitators to opioid tapering was useful in highlighting inequalities in relation to access; however, most of the qualitative studies explored experiences of opioid tapering in general, rather than in response to a specific tapering intervention. Process evaluations of opioid-tapering interventions undertaken as part of an effectiveness study therefore may be a valuable source of equality data.
Implications for practice/decision-makers
For clinicians and those organising and implementing tapering initiatives, these findings can help them to understand and address potential barriers that prevent patients initiating and engaging with an opioid taper. Knowing what barriers may arise at each stage of the tapering process can help providers better prepare for tapering, by identifying what facilitators may need to be put in place, at which points, to overcome the barriers. Our review findings validate the amendments made to the Levesque et al.55 framework by Voorhees et al.56 to consider both provider abilities to taper opioids and provider capacity to deliver opioid tapering. Due to the low quality and variability of the evidence identified, we are unable to come to any certain conclusions about the effectiveness of interventions for tapering opioids among people with chronic non-cancer pain. Interventions that combine dose tapering with support appear to be the most promising approach. Our findings also highlight the extent to which inequalities matter in relation to opioid tapering. The interpersonal characteristics of healthcare professionals may impact on inequalities, including the need to avoid stigmatising patients on chronic long-term opioid therapy and the importance of building trust to maintain a supportive patient–provider relationship. In addition, the findings of this review have important implications for the design and delivery of opioid-tapering interventions in avoiding widening inequalities to ensure access and accessibility to all. These findings have particular importance given the context of provision of care during the COVID-19 pandemic and move towards more remote forms of health care. Technology-based remote tapering initiatives should be careful not to discriminate against disadvantaged populations. In considering the impact of tapering implementation on inequalities, practitioners should remember that equal access does not necessarily equate with equality and, therefore, additional support for more disadvantaged populations may be required to reduce inequality gradients.