Introduction

In many clinical encounters the targeted treatment regime alone is unlikely to fully explain patients’ clinical outcomes [1]; the relationship between the patient and the clinician is also a critical component [2]. Working alliance (WA) is a construct that has been used to operationalise this professional relationship [3]. WA incorporates cognitive and emotional dimensions of the interpersonal processes between both parties occurring during care [4]. Research has demonstrated that WA is associated with physical function, pain, disability, patient satisfaction, adherence to the treatment plan and overall perceived effect of treatment [5–9].

The term WA originated from psychotherapy and there is uncertainty around its conceptualisation [4, 10]. This review adopted Bordin’s [11] formulation because it claims to be universally applicable [10–12]. According to Bordin [11], a person and a therapist, or in this case a chiropractor, unite against a common foe, for example, chronic low back pain, and work towards a common goal, such as improved physical function [10, 11]. A strong WA between the individual who strives for a change and the person who helps them (the change agent), is crucial for the change process itself and requires ongoing negotiation of expectations [11]. WA has three key features: shared decision making and agreement on goals of the change process, collaboration on the tasks required to achieve these goals, and establishment of a bond which is based on reciprocal feelings of liking [3, 11]. The mutual bond embraces interpersonal processes such as trust, acceptance and confidence and is often conceptualised in the literature in relation to patient’s perception of the therapist’s empathy [10, 13]. A systematic review of randomised control trials and cohort studies suggested that patients’ perception of the quality of the WA during treatment is a predictor for improved physical functioning and reduced pain in patients with chronic musculoskeletal pain: authors consequently recommended that practitioners should be sensitive to and enquire about patients’ perceptions of the WA [14].

Historically, chiropractors have identified themselves with a treatment predominantly focused on spinal manipulation. Increasingly however, evidence suggests that the idea of spinal manipulation being the single cause of observed clinical outcomes is unfounded given the evidential impact of contextual factors, which are part of all clinical encounters [15, 16]. Patients’ interpretation of these factors amongst which are interpersonal processes inherent in WA can trigger contextual effects through innate neurophysiological mechanisms and thus impact clinical outcomes [15]. Furthermore, it could be argued that strong WA can provide the foundational environment necessary for patients to benefit from the effects of contextual factors present in all chiropractic consultations [17] by eliciting psychological and/or behavioural changes [18]. For example, a large prospective cohort study illustrated that WA decreased disability at least partly by improving patients’ self-efficacy for coping and reducing psychosocial distress and the perceived threat of low back pain [5]. A more comprehensive understanding of WA will enable chiropractors to learn how to skilfully use contextual factors which in turn can drive modulation of pain [15].

To our knowledge, a review of the evidence base regarding the WA between a patient and a chiropractor has not been conducted. Consequently, this mixed methods systematic review aimed to synthesise qualitative and quantitative evidence to study the nature and the role of WA within chiropractic consultations. The qualitative component of this review identified and synthesised literature concerning patients’ and chiropractors’ perspective on the construct. The quantitative component reviewed additional literature investigating how WA and its features have been measured in the chiropractic literature and the effects of WA on clinical outcomes and patient satisfaction.