Evaluation of the Hospital Anxiety and Depression Scale (HADS) in screening stroke patients for symptoms: Item Response Theory (IRT) analysis.

BACKGROUND: Variations have been reported in the number of underlying constructs and choice of thresholds that determine caseness of anxiety and /or depression using the Hospital Anxiety and Depression scale (HADS). This study examined the properties of each item of HADS as perceived by stroke patients, and assessed the information these items convey about anxiety and depression between 3 months to 5 years after stroke. METHODS: The study included 1443 stroke patients from the South London Stroke Register (SLSR). The dimensionality of HADS was examined using factor analysis methods, and items' properties up to 5 years after stroke were tested using Item Response Theory (IRT) methods, including graded response models (GRMs). RESULTS: The presence of two dimensions of HADS (anxiety and depression) for stroke patients was confirmed. Items that accurately inferred about the severity of anxiety and depression, and offered good discrimination of caseness were identified as "I can laugh and see the funny side of things" (Q4) and "I get sudden feelings of panic" (Q13), discrimination 2.44 (se = 0.26), and 3.34 (se = 0.35), respectively. Items that shared properties, hence replicate inference were: "I get a sort of frightened feeling as if something awful is about to happen" (Q3), "I get a sort of frightened feeling like butterflies in my stomach" (Q6), and "Worrying thoughts go through my mind" (Q9). Item properties were maintained over time. LIMITATIONS: Approximately 20% of patients were lost to follow up. CONCLUSION: A more concise selection of items based on their properties, would provide a precise approach for screening patients and for an optimal allocation of patients into clinical trials.

Innovations in major system reconfiguration in England: a study of the effectiveness, acceptability and processes of implementation of two models of stroke care.

BACKGROUND: Significant changes in provision of clinical care within the English National Health Service (NHS) have been discussed in recent years, with proposals to concentrate specialist services in fewer centres. Stroke is a major public health issue, accounting for over 10% of deaths in England and Wales, and much disability among survivors. Variations have been highlighted in stroke care, with many patients not receiving evidence-based care. To address these concerns, stroke services in London and Greater Manchester were reorganised, although different models were implemented. This study will analyse processes involved in making significant changes to stroke care services over a short time period, and the factors influencing these processes. We will examine whether the changes have delivered improvements in quality of care and patient outcomes; and, in light of this, whether the significant extra financial investment represented good value for money. METHODS/DESIGN: This study brings together quantitative data on 'what works and at what cost?' with qualitative data on 'understanding implementation and sustainability' to understand major system change in two large conurbations in England. Data on processes of care and their outcomes (e.g. morbidity, mortality, and cost) will be analysed to evidence services' performance before and after reconfiguration. The evaluation draws on theories related to the dissemination and sustainability of innovations and the 'social matrix' underlying processes of innovation. We will conduct a series of case studies based on stakeholder interviews and documentary analysis. These will identify drivers for change, how the reconfigurations were governed, developed, and implemented, and how they influenced service quality. DISCUSSION: The research faces challenges due to: the different timings of the reconfigurations; the retrospective nature of the evaluation; and the current organisational turbulence in the English NHS. However, these issues reflect the realities of major systems change and its evaluation. The methods applied in the study have been selected to account for and learn from these complexities, and will provide useful lessons for future reconfigurations, both in stroke care and other specialties.