Publications
288 results found
Ashby D, Tan SB, 2005, Where's the utility in Bayesian data-monitoring of clinical trials?, CLINICAL TRIALS, Vol: 2, Pages: 197-205, ISSN: 1740-7745
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- Citations: 9
Grieve A, Lindley J, Goddard I, et al., 2004, Report of the Council for the session 2003-2004, Journal of the Royal Statistical Society. Series A: Statistics in Society, Vol: 167, Pages: 669-756, ISSN: 0964-1998
Cole TJ, Altman D, Ashby D, et al., 2004, BMJ statistical errors, BMJ, Vol: 329, ISSN: 0959-8138
Aldred G, Healy D, Mitchell AJ, et al., 2004, Antidepressants and suicide [4] (multiple letters), British Medical Journal, Vol: 329, Pages: 461-462, ISSN: 0959-8146
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- Citations: 1
Ashby D, 2004, Dicing with Death: Chance, Risk and Health, BMJ, Vol: 329, ISSN: 0959-8138
Gunnell D, Ashby D, 2004, Antidepressants and suicide: what is the balance of benefit and harm, BRITISH MEDICAL JOURNAL, Vol: 329, Pages: 34-38, ISSN: 0959-535X
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- Citations: 115
Preston C, Ashby D, Smyth R, 2004, Adjusting for publication bias: modelling the selection process, JOURNAL OF EVALUATION IN CLINICAL PRACTICE, Vol: 10, Pages: 313-322, ISSN: 1356-1294
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- Citations: 26
Eldridge SM, Ashby D, Feder GS, et al., 2004, Lessons for cluster randomized trials in the twenty-first century: a systematic review of trials in primary care., Clin Trials, Vol: 1, Pages: 80-90, ISSN: 1740-7745
BACKGROUND: Evidence suggests that cluster randomized trials are often poorly designed and analysed. There is little recent research on the methodologic quality of cluster randomized trials and none focuses on primary health care where these trials are increasingly common. METHODS: We conducted a systematic review of recent cluster randomized trials in primary health care, searching the Cochrane Controlled Trials Register. We also searched for unpublished trials in conference proceedings, and the UK National Research Register. We assess methodologic quality using a checklist, articulate problems facing investigators conducting these trials, and examine the extent to which carrying out a cluster randomized trial (as opposed to an individually randomized trial) in primary care may reduce power. RESULTS: We found 367 trial reports. Many trials were reported more than once. We characterize 152 independent cluster randomized trials in primary health care published between 1997 and 2000, and briefly describe 47 trials unpublished at December 2000. The quality of design and analysis was variable. Of published trials reporting sample size calculations 20% accounted for clustering in these calculations, 59% of published trials accounted for clustering in analyses. Unpublished trials were more recent and of higher quality. Reporting quality was better in journals reporting more cluster randomized trials. Many trial investigators reported problems with adherence to protocol, recruitment and type of intervention. CONCLUSIONS: Methodologic quality of cluster randomized trials in primary health care is variable and reporting needs improvement. The use of cluster randomization should be indicated in the title or abstract so these kinds of trials are easier to identify. Communicating appropriate methodology to health care researchers continues to be a challenge. Cluster randomized trials should always be piloted and information from pilots and unsuccessful trials shared more widely
Strobl J, Enzer I, Bagust A, et al., 2003, Using disease registries for pharmacoepidemiological research: a case study of data from a cystic fibrosis registry, PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Vol: 12, Pages: 467-473, ISSN: 1053-8569
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- Citations: 8
Rudnicka AR, Ashby D, Brennan P, et al., 2003, Thrombosis prevention trial - Compliance with warfarin treatment and investigation of a retained effect, ARCHIVES OF INTERNAL MEDICINE, Vol: 163, Pages: 1454-1460, ISSN: 0003-9926
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- Citations: 14
Golder M, Burleigh DE, Belai A, et al., 2003, Smooth muscle cholinergic denervation hypersensitivity in diverticular disease, LANCET, Vol: 361, Pages: 1945-1951, ISSN: 0140-6736
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- Citations: 91
Elphick HE, Tan A, Ashby D, et al., 2002, Systematic reviews and lifelong diseases, BMJ-BRITISH MEDICAL JOURNAL, Vol: 325, Pages: 381-384, ISSN: 1756-1833
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- Citations: 22
Mobbs KJ, Smyth RL, O'Hea U, et al., 2002, Cytokines in severe respiratory syncytial virus bronchiolitis, PEDIATRIC PULMONOLOGY, Vol: 33, Pages: 449-452, ISSN: 8755-6863
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- Citations: 29
Evans RC, Fear S, Ashby D, et al., 2002, Diet and colorectal cancer: An investigation of the lectin/galactose hypothesis, GASTROENTEROLOGY, Vol: 122, Pages: 1784-1792, ISSN: 0016-5085
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- Citations: 49
Dodge JA, 2001, Further comments on fibrosing colonopathy study., Lancet, Vol: 358, ISSN: 0140-6736
Harrison JE, Ashby D, 2001, Orthodontic treatment for posterior crossbites., Cochrane Database Syst Rev
BACKGROUND: 'Posterior crossbite' occurs when the top back teeth bite inside the bottom back teeth. When it affects one side of the mouth the lower jaw may have to move to one side to allow the back teeth to meet together. It is unclear what causes posterior crossbites and they may develop or improve at any time from when the baby teeth come into the mouth to when the adult teeth come through. Several treatments have been recommended to correct this problem. Some treatments widen the upper teeth whilst others are directed at treating the cause of the posterior crossbite e.g. breathing problems or sucking habits. Most treatments have been used at each stage of dental development. OBJECTIVES: The aim of this review was to evaluate orthodontic treatments used to expand the maxillary dentition and correct posterior crossbites. SEARCH STRATEGY: All randomised and controlled clinical trials identified from the Cochrane Controlled Trials Register according to the Oral Health Group Search Strategy and stored in the Cochrane Collaboration Oral Health Group Database of Clinical Trials, a MEDLINE search using the Mesh term Palatal Expansion Technique and relevant free text words, hand searching the British, European and American journals of orthodontics and Angle Orthodontist, and the bibliographies of papers and review articles which reported the outcome of orthodontic treatment to expand the maxillary dentition and/or correct a posterior crossbite that were published as abstracts or papers between 1970 and 1999. SELECTION CRITERIA: All randomised and controlled clinical trials published as full papers or abstracts which reported quantitative data on the outcomes crossbite correction, molar and/or canine expansion, signs and symptoms of temporomandibular joint dysfunction or respiratory disease. DATA COLLECTION AND ANALYSIS: Data were extracted without blinding to the authors, treatments used or results obtained. The first named authors of randomised and controlled clinical t
Poustie VJ, Watling RM, Ashby D, et al., 2000, Reliability of percentage ideal weight for height, ARCHIVES OF DISEASE IN CHILDHOOD, Vol: 83, Pages: 183-184, ISSN: 0003-9888
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- Citations: 21
Cheng K, Ashby D, Smyth R, 2000, Oral steroids for cystic fibrosis, Praxis, Vol: 89, Pages: 1157-1158, ISSN: 1661-8157
Cheng K, Ashby D, Smyth R, 2000, Oral steroids for cystic fibrosis., Cochrane database of systematic reviews (Online)
BACKGROUND: In cystic fibrosis, airway obstruction and recurrent respiratory infection leads to inflammation and eventually long term lung damage, (bronchiectasis), respiratory failure and death. Inflammation occurs early in the disease process, hence the rationale for the use of anti-inflammatory agents such as oral steroids. OBJECTIVES: To assess the effectiveness of oral steroids in management of respiratory complications cystic fibrosis with particular regard to lung function and occurrence of adverse events. We aimed to to examine short term use for a respiratory exacerbation separately (up to 30 days) from long term anti-inflammatory use (greater than 30 days). SEARCH STRATEGY: We searched The Cochrane Cystic Fibrosis and Genetic Disorders Group specialist trials register. Date of the most recent search of the Group's specialised register: November 1999. SELECTION CRITERIA: All randomised or pseudorandomised trials comparing oral corticosteroids given for a period of five to 30 days for treatment of an exacerbation or for more than 30 days used long term, with placebo or no additional therapy in patients with cystic fibrosis. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial eligibility and quality. MAIN RESULTS: Three trials were identified studying a total of 354 patients. Two of these were long term trials with four year follow up whilst one had follow up to 12 weeks only. There was a lack of data on our predefined outcomes with common outcomes examined at different time-points and also variations in the presentation of common outcomes. A meta-analysis was not possible. Oral corticosteroids at a prednisolone equivalent dose of 1 mg/kg alternate days appear to slow the progression of lung disease in cystic fibrosis. At 24 months from commencement, 70.4% patients treated with 1mg/kg prednisolone on alternate days had an increase in per cent predicted forced vital capacity (FVC) compared to 41.6% patients treated with placebo. The mean a
Cheng K, Smyth RL, Motley J, et al., 2000, Randomized controlled trials in cystic fibrosis (1966-1997) categorized by time, design, and intervention, PEDIATRIC PULMONOLOGY, Vol: 29, Pages: 1-7, ISSN: 8755-6863
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- Citations: 33
Harrison JE, Ashby D, 2000, Orthodontic treatment for posterior crossbites., Cochrane Database Syst Rev
BACKGROUND: 'Posterior crossbite' occurs when the top back teeth bite inside the bottom back teeth. When it affects one side of the mouth the lower jaw may have to move to one side to allow the back teeth to meet together. This movement may have long term effects on the growth of the teeth and jaws. It is unclear what causes posterior crossbites and they may develop or improve at any time from when the baby teeth come into the mouth to when the adult teeth come through. Several treatments have been recommended to correct them. Some treatments widen the upper teeth whilst others are directed at treating the cause of the posterior crossbite e.g. breathing problems or sucking habits. Most treatments have been used at each stage of dental development. OBJECTIVES: The aim of this review was to identify and evaluate orthodontic treatments used to expand the maxillary dentition and / or correct posterior crossbites. SEARCH STRATEGY: All randomised and controlled clinical trials identified from the Cochrane Controlled Trials Register according to the Oral Health Group Search Strategy and stored in the Cochrane Collaboration Oral Health Group Database of Clinical Trials, a MEDLINE search using the Mesh term and free text words, hand searching the British, European and American journals of orthodontics and Angle Orthodontist, and the bibliographies of papers and review articles which reported the outcome of orthodontic treatment to expand the maxillary dentition and/or correct a posterior crossbite that were published as abstracts or papers between 1970 and 1997 in English. SELECTION CRITERIA: All randomised and controlled clinical trials published as full papers or abstracts which reported quantitative data on the outcomes crossbite correction, molar and/or canine expansion, signs and symptoms of temporomandibular joint dysfunction or respiratory disease. DATA COLLECTION AND ANALYSIS: Data were extracted without blinding to the authors, treatments used or results obtained. T
Cheng K, Ashby D, Smyth R, 2000, Oral steroids for cystic fibrosis., Cochrane Database Syst Rev
BACKGROUND: In cystic fibrosis, airway obstruction and recurrent respiratory infection leads to inflammation and eventually long term lung damage, (bronchiectasis), respiratory failure and death. Inflammation occurs early in the disease process, hence the rationale for the use of anti-inflammatory agents such as oral steroids. OBJECTIVES: To assess the effectiveness of oral steroids in management of respiratory complications cystic fibrosis with particular regard to lung function and occurrence of adverse events. We aimed to to examine short term use for a respiratory exacerbation separately (up to 30 days) from long term anti-inflammatory use (greater than 30 days). SEARCH STRATEGY: We searched The Cochrane Cystic Fibrosis and Genetic Disorders Group specialist trials register. Date of the most recent search of the Group's specialised register: November 1999. SELECTION CRITERIA: All randomised or pseudorandomised trials comparing oral corticosteroids given for a period of five to 30 days for treatment of an exacerbation or for more than 30 days used long term, with placebo or no additional therapy in patients with cystic fibrosis. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial eligibility and quality. MAIN RESULTS: Three trials were identified studying a total of 354 patients. Two of these were long term trials with four year follow up whilst one had follow up to 12 weeks only. There was a lack of data on our predefined outcomes with common outcomes examined at different time-points and also variations in the presentation of common outcomes. A meta-analysis was not possible. Oral corticosteroids at a prednisolone equivalent dose of 1 mg/kg alternate days appear to slow the progression of lung disease in cystic fibrosis. At 24 months from commencement, 70.4% patients treated with 1mg/kg prednisolone on alternate days had an increase in per cent predicted forced vital capacity (FVC) compared to 41.6% patients treated with placebo. The mean a
White SJ, Ashby D, Brown PJ, 2000, An introduction to statistical methods for health technology assessment., Health Technol Assess, Vol: 4, Pages: i-59, ISSN: 1366-5278
Poustie VJ, Watling RM, Ashby D, et al., 1999, Taste preference for oral calorie supplements in children with cystic fibrosis, healthy children and healthy adults, JOURNAL OF HUMAN NUTRITION AND DIETETICS, Vol: 12, Pages: 301-306, ISSN: 0952-3871
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- Citations: 9
Bridgman CM, Ashby D, Holloway PJ, 1999, An investigation of the effects on children of tooth extraction under general anaesthesia in general dental practice, BRITISH DENTAL JOURNAL, Vol: 186, Pages: 245-247, ISSN: 0007-0610
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- Citations: 32
Ashby D, Smyth RL, Brown PJ, 1998, Statistical issues in pharmacoepidemiological case-control studies, STATISTICS IN MEDICINE, Vol: 17, Pages: 1839-1850, ISSN: 0277-6715
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- Citations: 6
Zelen M, Freedman D, Ashby D, et al., 1998, Clinician preferences and the estimation of causal treatment differences - Comments and rejoinder, STATISTICAL SCIENCE, Vol: 13, Pages: 228-235, ISSN: 0883-4237
Cheng K, Preston C, Ashby D, et al., 1998, Time to publication as full reports of abstracts of randomized controlled trials in cystic fibrosis, PEDIATRIC PULMONOLOGY, Vol: 26, Pages: 101-105, ISSN: 8755-6863
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- Citations: 30
Harrison JE, Ashby D, 1998, A systematic review of orthodontic treatment for posterior crossbites., JOURNAL OF DENTAL RESEARCH, Vol: 77, Pages: 784-784, ISSN: 0022-0345
Van Velzen D, Smith RL, Ashby D, 1997, Fibrosing colonopathy of pédiatrie cystic fibrosis patients related to the use of high-strength enzyme preparations, Pediatric Pathology and Laboratory Medicine, Vol: 17, ISSN: 1077-1042
Following the first recognition of fibrosing colonopathy (FC) in pédiatrie cystic fibrosis patients in the United Kingdom, a national study of the incidence of FC was carried out, sponsored by the United Kingdom Committee for the Safety in Medicine (CSM). The aim of the study was to identify all unequivocally diagnosed cases of FC in the UK. Using the National CF Registry, all CF patients in the UK alive between January 1, 1984 and January 7, 1994 were screened for invasive surgical procedures as of the first year of life. All procedures were reviewed for the possibility of review of sufficient tissue samples for the diagnosis of FC on a histopathological basis. All surgical pathology reports indicating the removal of sufficient tissue specimens were followed up by three pathology reviews of all available slides. Final classification was based on at least two pathologists confidently classifying a case as FC. A number of factors possibly of interest to the pathogenesis of FC (among others, total enzyme dose, type and brand of preparations used, etc.) were studied for their statistical association with FC through a nested case-control study with four agematched but otherwise completely random controls for each case. Fourteen cases of FC (13 unanimous, 1 on majority rule), 13 males and 1 female patient, age range 1.5 to 13 years, were established as having been operated for the condition between April 1992 and July 1994 in the population of CF patients, which averaged 6000 patients. The specimens feature a highly consistent pathology with fusiform stenosis of the ascending colon due to submucosal widening by quiescent fibrosis, beginning in the cecum and often extending far distal to the site of most severe stenosis. A generally intact mucosa showed regular areas of recent reepithelization. No other specific abnormality was noted, and the terminal ileum, separate from occasional minor inflammation and a variable degree of submucosal edema, showed no abnormaliti
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