2 - Schools incorporating the Life Sciences and Medicine
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Item Single imputation methods were inadequate for missing not at random (MNAR) quality of life data(BMC, 2008-08-04) Fielding, Shona; Fayers, Peter; McDonald, Alison Mary; McPherson, Gladys Campbell; Campbell, Marion Kay; RECORD Study Group; University of Aberdeen, School of Medicine & Dentistry, Division of Applied Health SciencesObjective: QoL data were routinely collected in a randomised controlled trial (RCT), which employed a reminder system, retrieving about 50% of data originally missing. The objective was to use this unique feature to evaluate possible missingness mechanisms and to assess the accuracy of simple imputation methods. Methods: Those patients responding after reminder were regarded as providing missing responses. A hypothesis test and a logistic regression approach were used to evaluate the missingness mechanism. Simple imputation procedures were carried out on these missing scores and the results compared to the actual observed scores. Results: The hypothesis test and logistic regression approaches suggested the reminder data were missing not at random (MNAR). Reminder-response data showed that simple imputation procedures utilising information collected close to the point of imputation (last value carried forward, next value carried backward and last-and-next), were the best methods in this setting. However, although these methods were the best of the simple imputation procedures considered, they were not sufficiently accurate to be confident of obtaining unbiased results under imputation. Conclusion: The use of the reminder data enabled the conclusion of possible MNAR data. Evaluating this mechanism was important in determining if imputation was useful. Simple imputation was shown to be inadequate if MNAR are likely and alternative strategies should be considered.Item Protocol for stage 2 of the GaP study (genetic testing acceptability for Paget's disease of the bone) : a questionnaire study to investigate whether relatives of people with Paget's disease would accept genetic testing and preventative treatment if they were available(BioMed Central, 2008-05-29) Langston, Anne L.; Johnston, Marie; Francis, Jillian Joy; Robertson, Clare; Campbell, Marion Kay; Entwistle, Vikki; Marteau, Theresa; MacLennan, Graeme Stewart; Weinman, John; McCallum, Marilyn; Miedzybrodzka, Zosia; Charnock, Keith; Ralston, Stuart H.; University of Aberdeen, School of Medicine & Dentistry, Division of Applied Health SciencesBackground: Paget's disease of bone (PDB) disrupts normal bone architecture and causes pain, deformity, deafness, osteoarthritis, and fractures. Genetic factors play a role in PDB and genetic tests are now conducted for research purposes. It is thus timely to investigate the potential for a clinical programme of genetic testing and preventative treatment for people who have a family history of PDB. This study examines the beliefs of relatives of people with PDB. It focuses particularly on illness and treatment representations as predictors of the acceptability and uptake of potential clinical programmes. Illness representations are examined using Leventhal's Common Sense Self-Regulation Model while cognitions about treatment behaviours (acceptance of testing and treatment uptake) are conceptualised within the Theory of Planned Behaviour. Methods/Design: A postal questionnaire of non-affected relatives of people with Paget's disease. The sample will include relatives of Paget's patients with a family history of Paget's disease and relatives of Paget's patients without a family history of Paget's disease. The questionnaire will explore whether a range of factors relate to acceptability of a programme of genetic testing and preventive treatment in relatives of Paget's disease sufferers. The questionnaire will include several measures: illness representations (as measured by the Brief Illness Perceptions Questionnaire); treatment representations (as measured by Theory of Planned Behaviour-based question items, informed by a prior interview elicitation study); descriptive and demographic details; and questions exploring family environment and beliefs of other important people. Data will also be collected from family members who have been diagnosed with Paget's disease to describe the disease presentation and its distribution within a family. Discussion: The answers to these measures will inform the feasibility of a programme of genetic testing and preventive treatment for individuals who are at a high risk of developing Paget's disease because they carry an appropriate genetic mutation. They will also contribute to theoretical and empirical approaches to predicting diagnostic and treatment behaviours from the combined theoretical models.