In structuring decision models of medical interventions, it is commonly recommended that only 2 branches be used for each chance node to avoid logical inconsistencies that can arise during sensitivity analyses if the branching probabilities do not sum to 1. However, information may be naturally available in an unconditional form, and structuring a tree in conditional form may complicate rather than simplify the sensitivity analysis of the unconditional probabilities. Current guidance emphasizes using probabilistic sensitivity analysis, and a method is required to provide probabilistic probabilities over multiple branches that appropriately represents uncertainty while satisfying the requirement that mutually exclusive event probabilities should sum to 1. The authors argue that the Dirichlet distribution, the multivariate equivalent of the beta distribution, is appropriate for this purpose and illustrate its use for generating a fully probabilistic transition matrix for a Markov model. Furthermore, they demonstrate that by adopting a Bayesian approach, the problem of observing zero counts for transitions of interest can be overcome.

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Patient and physician perspectives on the impact and management of perennial (PAR) and seasonal allergic rhinitis (SAR) were studied. In all, 2139 subjects were questioned about their medical conditions, severity and frequency of symptoms and satisfaction with treatment. A group of general practitioners (GPs) were also invited to discuss their experiences in the management of rhinitis. In this UK survey, allergic rhinitis was more common than asthma, hypertension, skin rashes, eczema and diabetes. The prevalence of SAR and PAR was 15% and 2%, respectively. Sneezing and runny nose were the most common symptoms and GPs were the main contact for advice and treatment (54% of patients). Symptoms were well-controlled in 32% of patients. Allergic rhinitis affected work, home and social life in 29%, 34% and 30% of patients, respectively. The GPs considered PAR to be more difficult to treat than SAR, and GP and patient level of satisfaction in the treatment of PAR was low. This suggests that education of patients and physicians on the benefits of allergen avoidance, and the selective use of the highly effective therapies available on prescription could improve the level of satisfaction with therapy. Adherence to current guidelines on the management of rhinitis could lead to an effective, structured treatment plan for patients.

This is one of the first decision-analytic models of asthma to incorporate probabilistic sensitivity analysis techniques to explore uncertainty. The model's flexible yet standardised framework permits the cost effectiveness of alternative asthma management strategies in different healthcare settings to be established.

Risperidone long acting injection (RLAI) is the only long acting atypical antipsychotic available in the UK. Its impact on NHS resource use has not been widely studied. This review of medical records was conducted to quantify the impact of RLAI on NHS psychiatric secondary care resource use, primarily in terms of episodes of inpatient hospital care 12 months before and 12 months after RLAI initiation. Data on number of hospitalizations and hospital bed days were collected retrospectively, from patient notes and hospital databases in four acute psychiatric units in the UK for all individuals with a diagnosis of schizophrenia or schizoaffective disorder who were prescribed RLAI more than 12 months previously. Data were collected on 100 individuals (58 male) with a mean age 40.8 years (range 19-70). The median duration of illness before RLAI initiation was 12 years (range six months to 43 years). There were 62 admissions in the 12 months pre-RLAI, falling to 22 admissions in the 12 months post-RLAI. Number of admissions, we argue, offer a more reliable indicator of the impact of treatment than total hospital bed days in this type of study. In this study there were 40 fewer admissions in the 12 months after RLAI was initiated compared with the previous 12 months. This is important as readmission is a good proxy measure of relapse, and adherence to medication is known to be a key factor in relapse prevention.