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Duration of psychological therapy: Relation to recovery and improvement rates in UK routine practice

  • William B. Stiles (a1), Michael Barkham (a2) and Sue Wheeler (a3)

Previous studies have reported similar recovery and improvement rates regardless of treatment duration among patients receiving National Health Service (NHS) primary care mental health psychological therapy.


To investigate whether this pattern would replicate and extend to other service sectors, including secondary care, university counselling, voluntary sector and workplace counselling.


We compared treatment duration with degree of improvement measured by the Clinical Outcomes in Routine Evaluation – Outcome Measure (CORE-OM) for 26 430 adult patients who scored above the clinical cut-off point at the start of treatment, attended 40 or fewer sessions and had planned endings.


Mean CORE-OM scores improved substantially (pre–post effect size 1.89); 60% of patients achieved reliable and clinically significant improvement (RCSI). Rates of RCSI and reliable improvement and mean pre- and post-treatment changes were similar at all tested treatment durations. Patients seen in different service sectors showed modest variations around this pattern.


Results were consistent with the responsive regulation model, which suggests that in routine care participants tend to end therapy when gains reach a good-enough level.

Corresponding author
Dr William B. Stiles, PO Box 27, Glendale Springs, North Carolina 28629, USA. Email:
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See editorial, pp. 93–94, this issue.

Declaration of interest

M.B. was a developer of the CORE measures.

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  • ISSN: 0007-1250
  • EISSN: 1472-1465
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Supplementary Table S1-S2

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Duration of psychological therapy: Relation to recovery and improvement rates in UK routine practice

  • William B. Stiles (a1), Michael Barkham (a2) and Sue Wheeler (a3)
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