The cost of bipolar disorder to the NHS was estimated to be £342 million in 2010, and estimates of the cost to society as a whole rise to more than £5 billion. As such, it’s important that we can identify cost-effective treatments that help reduce the burden for patients as well as giving the economy a boost. Demonstrating that a treatment is effective is no longer sufficient.

A systematic review of economic evaluations in bipolar disorder was recently published (Abdul Pari et al, 2014).

Methods

The study aimed to do a number of things:

1. Identify existing economic studies in bipolar disorder
2. Help readers understand why there is variability in the available evidence
3. Highlight challenges in evaluating chronic mental health problems
4. Identify future research priorities

The authors searched for studies published between 1980 and 2012 that provided data on the cost-effectiveness of any management strategy for bipolar disorder, using a total of 7 electronic databases. Only studies comparing 2 or more options that considered both costs and outcomes were included, and the quality of studies was assessed in accordance with Cochrane Collaboration recommendations.

Results

The initial search identified 4,467 unique studies, with 317 progressing to abstract screening. A total of 20 studies were ultimately included in the review:

• 9 were from the USA and 7 from the UK
• 14 of the studies evaluated pharmaceutical interventions
• 15 studies looked at preventive treatments
• 5 studies were trial-based and 15 were model-based economic evaluations

Trial-based studies

• For trial-based evaluations, most were cost-consequences analyses (which is where costs and outcomes are not combined into a single result)
• The number of participants ranged from 52 to 331 with follow-up periods between 12 weeks and 36 months
• Only one of the trial-based studies aggregated costs and outcomes into an incremental cost-effectiveness ratio
• These studies presented favourable results for collaborative and psychological therapies but not pharmaceutical options
• However, none of the trial-based studies could be classified as having a low risk of bias

Model-based studies

• Most of the model-based studies evaluated pharmaceutical interventions, and a number of options were shown to be cost-effective
• However, a lot of variation was found in the design and quality of the model-based evaluations. There was:
  • 1 decision tree
  • 8 cohort Markov models
  • 2 discrete event simulations
  • 2 based on a mathematical model
  • 2 that failed to state their structure
• The quality of the modelling studies varied greatly, with only 2 scoring above 80% on the quality checklist
• Five of the studies reported favourable results for quetiapine or quetiapine+lithium,
• One study favoured a collaborative care model
• Another study supported CBT

Conclusion

The authors concluded that:

Given the variability in the methods and quality of the identified studies, it is difficult to provide a conclusive recommendation for the most cost-effective therapy for bipolar disorder based on existing evidence.

Future research recommendations

Bipolar disorder is costly to society, so it’s surprising that more economic evaluations have not been funded. As the review was unable to provide any definitive answers, the study instead makes a number of proposals for future research. The authors recommend:

• Transparent description of comparators
• Use of a broad societal (cost) perspective
• Extrapolation of findings using decision analytic models
  • Preferably using discrete event simulation
  • Including all relevant comparators
  • Using a lifetime horizon
• Use of multi-attribute utility scales as well as condition-specific outcomes
• Appropriate handling of missing data
• Presentation of results in both aggregated and disaggregated form
• Use of probabilistic sensitivity analysis
• Decisions about funding interventions should be based on a wider empirical framework

Links

Abdul Pari AA, Simon J, Wolstenholme J, Geddes JR, Goodwin GM. Economic evaluations in bipolar disorder: a systematic review and critical appraisal. Bipolar Disorders 2014; 16: 557–582. Available: http://dx.doi.org/10.1111/bdi.12213. [PubMed]