Background The therapeutic relationship is complex and incompletely captured in objective metrics.

Aim To review the different concepts, theoretical models and empirical approaches which researchers have used to capture in qualitative terms what is special about the relationship between practitioner and patient.

Method Drawing on the principles of meta-narrative systematic review (but without seeking an exhaustive inventory of every paper ever published), we considered different research traditions in terms of their respective philosophical assumptions, methodological strengths and limitations and empirical findings. We applied published quality criteria from each tradition to papers within that tradition.

Results Four research approaches were oriented to producing subjective interpretations of quality in the therapeutic relationship. These had emerged in different research traditions: psychodynamic (eg, the Balint method, whose roots are in psychoanalysis); narrative (literary theory, moral philosophy); critical consultation analysis (critical sociology) and socio-technical analysis (actor-network theory). Each emphasised a different dimension of relationship quality.

Conclusion Subjective (interpretive) approaches do not lend themselves readily to metrics or scales, but they can inform a structured list of questions to prompt practitioner reflection. A combination of objective metrics and reflective practice has considerable quality improvement potential.