Effectiveness of psychological therapies for depression or anxiety in adults with intellectual disabilities: retrospective, matched, observational cohort study of primary care electronic healthcare records in England

Background: Treatment guidelines recommend evidence-based psychological therapies for adults with intellectual disabilities with co-occurring anxiety or depression. No previous research has explored the effectiveness of these therapies in mainstream psychological therapy settings or outside specialist settings. Aims: To evaluate the effectiveness of psychological therapies delivered in routine primary care settings for people with intellectual disability who are experiencing co-occurring depression or anxiety. Method: This study used linked electronic healthcare records of 2 048 542 adults who received a course of NHS Talking Therapies for anxiety and depression in England between 2012 and 2019 to build a retrospective, observational cohort of individuals with intellectual disability, matched 1:2 with individuals without intellectual disability. Logistic regressions were used to compare metrics of symptom improvement and deterioration used in the national programme, on the basis of depression and anxiety measures collected before and at the last attended therapy session. Results: The study included 6870 adults with intellectual disability and 2 041 672 adults without intellectual disability. In unadjusted analyses, symptoms improved on average for people with intellectual disability after a course of therapy, but these individuals experienced poorer outcomes compared with those without intellectual disability (reliable improvement 60.2% for people with intellectual disability v. 69.2% for people without intellectual disability, odds ratio 0.66, 95% CI 0.63–0.70; reliable deterioration 10.3% for people with intellectual disability v. 5.7% for those without intellectual disability, odds ratio 1.89, 95% CI 1.75–2.04). After propensity score matching, some differences were attenuated (reliable improvement, adjusted odds ratio 0.97, 95% CI 1.91–1.04), but some outcomes remained poorer for people with intellectual disability (reliable deterioration, adjusted odds ratio 1.28, 95% CI 1.16–1.42). Conclusions: Evidence-based psychological therapies may be effective for adults with intellectual disability, but their outcomes may be similar to (for improvement and recovery) or poorer than (for deterioration) those for adults without intellectual disability. Future work should investigate the impact of adaptations of therapies for those with intellectual disability to make such interventions more effective and accessible for this population.