Principal findings and interpretation

This was the first study to employ data-linkage methodology to examine longitudinal medication usage trends among psychological therapy service-users with moderate-to-severe mental health problems. Unsurprisingly, as hypothesised, service-users were significantly more likely than matched controls to be in receipt of hypnotics/anxiolytics and antidepressant medications during the 1st and 2nd years before referral for therapy. However, less predictably given the remit of the therapy service examined, more than one-fifth of therapy clients had received at least one antipsychotic prescription in the year before referral for therapy; a considerably higher rate than that found among controls.

Findings relevant to the second study hypothesis were more equivocal. Although rates of anxiolytic medication use fell after discharge for all therapy clients regardless of their engagement or therapeutic progress, service-users who exhibited clinically significant improvement after therapy were only more likely to come off anxiolytic medication earlier (i.e. 1st year after discharge) than those who did not clinically improve or those who failed to engage in therapy. The data suggest that all therapy client groups tended to remain on antipsychotic and antidepressant medication for as long as 2 years post therapy discharge. Before and after therapy, individuals who failed to engage with therapy were more likely to be prescribed intensive medication subtypes such as anxiolytics or antipsychotics, which suggests these individuals may be a particular at-risk population.

Comparison with previous literature

The present study found high rates of antipsychotic prescribing to service-users, despite only a small proportion of these clients being assessed by clinicians as having psychotic symptoms. Other studies have highlighted this discrepancy between prescription rates for antipsychotics and diagnoses of psychosis, noting that rates of antipsychotic prescribing have been rising faster than psychosis incidence.^{Reference Shoham, Cooper, Lewis, Bebbington and McManus19} A UK cohort study also found high rates of antipsychotic prescribing to patients without psychosis and concluded that this reflected psychotropic management of conditions such as depression or anxiety, despite national guidelines recommending that antipsychotics are not clinically indicated for such disorders.^{Reference Marston, Nazareth, Petersen, Walters and Osborn20,21} Clinicians in routine practice may be prescribing antipsychotics (often at low dose) to exert a tranquillising effect and control general features of mental health presentations such as agitation, poor sleep and anxiety.^{Reference Marston, Nazareth, Petersen, Walters and Osborn20} Although such prescribing patterns are aimed at alleviating acute symptoms, they can lead to negative long-term side-effects and are a controversial practice.^{Reference Carroll22} Subthreshold psychotic experiences are common in the general public and may also occur, for example, in populations who were clinically depressed or individuals meeting clinical high risk for psychosis criteria.^{Reference McGrath, Saha, Al-Hamzawi, Alonso, Bromet and Bruffaerts23} However, treatment guidelines oppose the use of antipsychotic medications within these populations as there is little evidence for their effectiveness or capacity to reduce risk of transition to psychotic disorder.²¹

Previously, Sreeharan et al ^{Reference Sreeharan, Madden, Lee, Millett and Majeed9} concluded, based on group-level data from Improving Assess to Psychological Therapy services in England, that psychological interventions had not altered the long-term upward trend in antidepressant prescriptions. The current study involved a UK-based secondary care psychological therapy service that analysed individual level, as opposed to group-level, data, thereby supporting stronger conclusions regarding the impact of therapy on prescription trends. Consistent with Sreeharan et al,^{Reference Sreeharan, Madden, Lee, Millett and Majeed9} the present results show that therapy does not appear to alter the likelihood of an individual coming off antidepressants, even when the client reports that their psychological well-being has improved. The findings also highlight that a variety of medication types (e.g. antianxiety, antipsychotics) show little evidence of prescribing reduction following therapy. Interpretations of such results could include that, despite apparent clinical improvement on symptom measures, psychological therapy may be less effective in alleviating mental health difficulties than self-reported questionnaires indicate, thereby leading to limited change in psychotropic medication usage. However, this contradicts the psychometric literature highlighting that self-ratings of mental health symptoms are less biased than alternative methods (e.g. clinician ratings), as well as the wealth of evidence supporting the clinical effectiveness of comparable models of psychological therapy delivery.^{Reference Clark24,Reference Zimmerman, Walsh, Friedman, Boerescu and Attiullah25} The moderate reduction in antianxiety medication in patients who exhibited clinically significant improvement after therapy suggests that some transdiagnostic anxiety management elements of psychological therapy may be effective in the year following intervention (e.g. relaxation, thought challenging, graded exposure). Nevertheless, the long-term maintenance of these treatment gains may be more challenging and require additional post therapy elements of psychological support (e.g. peer support groups).^{Reference Pistrang and Barker26}

Strengths and limitations

A key strength of this study lies in its use of data-linkage methodology. This represents a modern, cost-effective, and efficient approach to healthcare research²⁷ and can make maximal use of existing data sources to understand the wider impact of psychological therapies on mental health. Consequently it would be beneficial for other services to record relevant outcomes data to support matching to population databases. A successful match to healthcare records was established in the present study for the vast majority (85%) of therapy clients. It is not possible to determine exactly why the matching process failed for some clients; however, errors could have been present in the therapies or prescriptions data-sets.

The findings of the current investigation have external validity considering the clinical sample is comprehensive and representative of patients of a community psychological therapy service. However, it must be acknowledged that because of data limitations it was not possible to compare subpopulations of diagnoses (e.g. major depressive disorder) or specific medication usage, nor to examine dosing ranges or source of prescription (e.g. primary or secondary care). Moreover, the categorisation of patient presenting problems were made by clinician judgement following intake assessment and intervention on a bespoke assessment proforma, rather than a formal diagnostic schedule.

The present study provides important insights into prescribing use among a population seeking help for mental health problems in Northern Ireland. It is possible different patterns could be found in other regions, as prescribing rates are generally higher in Northern Ireland^{Reference McClure5} compared with the rest of the UK and prescribing rates tend to vary in accordance with population demographics. For example, higher levels of prescribing are often found in areas with higher population density and higher social disadvantage.^{Reference Heald, Stedman, Farman, Khine, Davies and De Hert28} Further, research to explore the impact of therapy on prescribing trends in other countries will help to establish if the trends in the present study are widespread.

Implications

Similar to other data-linkage studies, the present analyses have highlighted possible discrepancies between clinical guidelines and prescribing practice.^{Reference Henderson, Kinnear, Fleming, Stanley, Greenlaw and Young-Southward11} The current study found that as many as 21% of therapy service clients had received an antipsychotic prescription in the year before therapy, considerably higher than the 2% of clients that present to the service with psychosis symptoms. This is also alarming considering patients in the current sample were more likely to present mixed anxiety and depression, mood disorders, anxiety, PTSD or OCD. Clinical practice guidelines advise against the use of antipsychotics for anxiety disorders,²⁹ and recommend the use of antipsychotics for mood disorders such as depression where comorbid psychosis symptoms occur.³⁰ Antipsychotics are also not recommended as first- line treatment for PTSD, and should only be considered as an adjunct to therapy if the client has disabling symptoms and behaviours (e.g. hyperarousal or psychotic symptoms) or their symptoms have not responded to other drug or psychological treatments.³¹ This pattern of enhanced antipsychotic prescribing needs further exploration. Clinical practice guidelines reflect gold-standard generic intervention recommendations, however, the idiographic nature of routine practice is more complex and may necessitate straying beyond standard conventions to support individual patient needs (e.g. off-license prescribing). Nevertheless, complacent acceptance of such a potential explanation may obscure other factors such as broader cultural trends in prescribing and lack of timely access to alternative therapies.

Patients on antidepressants continued to receive prescriptions for their medication regardless of therapy outcome in the 1st year after discharge. This finding is consistent with National Institute for Health and Care Excellence guidelines³⁰ that recommend that for depression patients should continue use for at least 6 months after remission as this reduces the risk of relapse, and such medications are not associated with dependence. However, it is possible that post therapy antidepressant continuance extends for a longer period than required, potentially because of a lack of ongoing review and tapering schedule; acceptance of the minimal side-effect profile while taking the drugs; and genuine unease in both clinicians and clients about potential relapse if withdrawn.^{Reference Wilson and Lader32}

Although the 1-year reduction in anxiolytics/hypnotics post-therapy suggests an anxiety-reducing effect of psychological interventions, the limited long-term decrease in clients who reported clinical improvement after therapy is also concerning. Guidelines are clear that benzodiazepine should be used as a short-term measure in the treatment of generalised anxiety disorder to manage crises due in part to the well-established risks of dependence.²⁹ Several interventions could assist clinicians in this complex area. Wilson & Lader^{Reference Wilson and Lader32} emphasise the need for further education and training for clinicians and clients to ensure effective decision-making with regard to appropriate medication discontinuance, particularly after successful psychological intervention. More effective integration and multidisciplinary decision-making on elements of treatment (e.g. medication, psychological therapies) in a collaborative care model, could also be instrumental in improving post-therapy prescribing levels.