Jill Porthouse

The University of York, York, England, United Kingdom

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Publications (13)70.06 Total impact

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    ABSTRACT: OBJECTIVES: To identify participants' characteristics that influence the anti-fracture efficacy of vitamin D or vitamin D plus calcium with respect to any fracture, hip fracture, and clinical vertebral fracture and to assess the influence of dosing regimens and co-administration of calcium. DESIGN: Individual patient data analysis using pooled data from randomised trials. DATA SOURCES: Seven major randomised trials of vitamin D with calcium or vitamin D alone, yielding a total of 68 517 participants (mean age 69.9 years, range 47-107 years, 14.7% men). STUDY SELECTION: Studies included were randomised studies with at least one intervention arm in which vitamin D was given, fracture as an outcome, and at least 1000 participants. DATA SYNTHESIS: Logistic regression analysis was used to identify significant interaction terms, followed by Cox's proportional hazards models incorporating age, sex, fracture history, and hormone therapy and bisphosphonate use. RESULTS: Trials using vitamin D with calcium showed a reduced overall risk of fracture (hazard ratio 0.92, 95% confidence interval 0.86 to 0.99, P=0.025) and hip fracture (all studies: 0.84, 0.70 to 1.01, P=0.07; studies using 10 microg of vitamin D given with calcium: 0.74, 0.60 to 0.91, P=0.005). For vitamin D alone in daily doses of 10 microg or 20 microg, no significant effects were found. No interaction was found between fracture history and treatment response, nor any interaction with age, sex, or hormone replacement therapy. CONCLUSION: This individual patient data analysis indicates that vitamin D given alone in doses of 10-20 microg is not effective in preventing fractures. By contrast, calcium and vitamin D given together reduce hip fractures and total fractures, and probably vertebral fractures, irrespective of age, sex, or previous fractures.
    BMJ British medical journal 01/2010; 340:b5463. · 16.30 Impact Factor
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    ABSTRACT: Seasonal Affective Disorder (SAD) is a sub-type of depression that only occurs during the winter months. A reduction in vitamin D may be linked to SAD. Since vitamin D deficiency has been reported to be common in older people, vitamin D supplementation may be expected to reduce seasonal mood disturbance in this group. To assess the effect of vitamin D supplementation on the mental health of older women. Primary care in three areas of the UK (Herts, Newcastle, York). Women aged 70 years or more recruited to the trial in the months May-October. Intervention: Eligible women were randomised to receive calcium and vitamin D supplementation or no supplementation. At baseline and the six monthly assessment the mental component score (MCS), calculated from the SF-12 questionnaire was used to assess participants' subjective psychological well-being. A total of 2117 women recruited to the trial had their baseline measures taken between the months of May-October (1205 woman in the control group and 912 women in the intervention group). Of these women, 1621 had a MCS score at baseline and six months. Comparison of the six month mean MCS scores, adjusting for baseline MCS score and age, showed there was no significant difference between the two scores (p = 0.262). Supplementing elderly women with 800 IU of vitamin D daily did not lead to an improvement in mental health scores.
    The Journal of Nutrition Health and Aging 01/2006; 10(2):151-3. · 2.39 Impact Factor
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    ABSTRACT: Health care and educational trials face similar methodological challenges. Methodological reviews of health care trials have shown that a significant proportion have methodological flaws. Whether or not educational trials have a similar proportion of poor-quality trials is unknown. The authors undertook a methodological comparison between health care and educational trials published since 1990. The authors aimed (1) to assess whether the quality of trial reports in education and health care are similar; and (2) to assess whether trial reporting quality is improving. The characteristics of a sample of trials, published since 1990, were taken from health and educational journals. Trials were assessed using the following quality criteria: rationale for sample size; concealment of allocation; blinded follow-up; use of confidence intervals; adequate sample size. Ninety-six placebo drug trials and 54 non-drug trials published in major general journals were identified. These were compared with 54 trials in specialist health journals and 84 trials in educational journals. No educational trial used concealed allocation or reported the rationale for sample size calculation and only one trial used confidence intervals. There was a trend for the reporting of health care trials to improve with time, whilst the reporting quality of educational trials declined. The authors concluded that poor quality of trial reporting is more prevalent in educational journals than in health care journals.
    British Educational Research Journal 12/2005; · 1.50 Impact Factor
  • Carole Torgerson, Jill Porthouse, Greg Brooks
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    ABSTRACT: This paper reports a systematic review of the quasi-experimental literature in the field of adult literacy and numeracy, published between 1980 and 2002. We included 27 controlled trials (CTs) that evaluated strategies and pedagogies designed to increase adult literacy and numeracy: 18 CTs with no effect sizes (incomplete data) and 9 CTs with full data. These nine trials are examined in detail for this paper. Of these nine trials, six evaluated interventions in literacy and three evaluated interventions in literacy and numeracy. Three of the nine trials showed a positive effect for the interventions, five trials showed no difference and one trial showed a positive effect for the control treatment. The quality of the trials was variable, but many of them had some methodological problems. There was no evidence of publication bias in the review. There have been few attempts to expose common adult literacy or numeracy programmes to rigorous evaluation and therefore in terms of policy and practice it is difficult to make any recommendations as to the type of adult education that should be supported. In contrast, however, the review does provide a strong steer for the direction to be taken by educational researchers: because of the present inadequate evidence base rigorously designed randomised controlled trials and quasi-experiments are required as a matter of urgency.
    Journal of Research in Reading 05/2005; 28(2):87 - 107. · 1.25 Impact Factor
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    ABSTRACT: To assess whether supplementation with calcium and cholecaliferol (vitamin D3) reduces the risk of fracture in women with one or more risk factors for fracture of the hip. Pragmatic open randomised controlled trial. Practice nurse led clinics in primary care. 3314 women aged 70 and over with one or more risk factors for hip fracture: any previous fracture, low body weight (< 58 kg), smoker, family history of hip fracture, or fair or poor self reported health. Daily oral supplementation using 1000 mg calcium with 800 IU cholecaliferol and information leaflet on dietary calcium intake and prevention of falls, or leaflet only (control group). Primary outcome measure was all clinical fractures and secondary outcome measures were adherence to treatment, falls, and quality of life (measured with the SF-12). 69% of the women who completed the follow-up questionnaire at 24 months were still taking supplements (55% with inclusion of randomised participants known to be alive). After a median follow-up of 25 months (range 18 to 42 months), clinical fracture rates were lower than expected in both groups but did not significantly differ for all clinical fractures (odds ratio for fracture in supplemented group 1.01, 95% confidence interval 0.71 to 1.43). The odds ratio for hip fracture was 0.75 (0.31 to 1.78). The odds of a woman having a fall at six and 12 months was 0.99 and 0.98, respectively. Quality of life did not significantly differ between the groups. We found no evidence that calcium and vitamin D supplementation reduces the risk of clinical fractures in women with one or more risk factors for hip fracture. Registration ISRCTN26118436, controlled trials registry.
    BMJ (online) 04/2005; 330(7498):1003. · 17.22 Impact Factor
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    ABSTRACT: Low response rates to postal questionnaires can threaten the validity of studies by reducing the effective sample size and introducing bias. The identification of methods with which to optimise response rates could, therefore, improve the quality of studies. In an attempt to identify such methods, we undertook a randomised trial of two simple variations in questionnaire design. Using a 2 x 2 factorial design, we conducted a randomised trial to test two variations in questionnaire design; the questionnaires were printed on either single-sided or double-sided paper and had either a single- or multiple-booklet layout. Using equal random allocation, 3836 women were randomised to receive one of these questionnaires as part of a study investigating risk factors for osteoporotic fractures. One thousand eight hundred and seventy questionnaires were returned, giving an overall response rate of 48.7%. There were no significant differences in the overall response to each of the four questionnaire designs. When the number of responders who completed at least 50% of each of the three sections was identified, it was found that single-booklet questionnaires had a better response than the multiple-booklet questionnaires and that single-sided questionnaires had a better response than double-sided questionnaires. However, these results were not significant at the 5% level. There were no significant differences in the response to questions on the odd (left-hand side) pages for the single- compared with the double-sided questionnaires. As the most cost-effective use of resources, we would advocate the use of double- rather than single-sided questionnaires, and use of a single- rather than multiple-booklet design.
    Journal of Health Services Research & Policy 11/2004; 9(4):213-7. · 1.73 Impact Factor
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    ABSTRACT: To assess whether hip protectors used among women living in the community in the United Kingdom and at high risk of hip fracture, lead to a reduction in hip fracture. Pragmatic randomized controlled trial (RCT). Primary care with participants being recruited largely from general practitioners' patient lists. Women aged 70 years and over with one or more risk factors for hip fracture (i.e., low body weight, current smoker, a prior fracture, family history of hip fracture). Three pairs of hip protectors of the "shell" type mailed to participants with instructions on how to use them. Reduction in hip fractures. 1,388 and 2,781 women aged 70 years or over were randomized to be given three pairs of hip protectors or act as controls, respectively. We followed up both groups of women for a minimum of 24 months (maximum 42 months, median 28). Compliance was poor with only 31% of participants reporting that they wore the hip protectors on a daily basis at 12 months. Intention-to-treat analysis showed that there was no statistically significant difference in the unadjusted odds ratios (ORs) of sustaining a hip fracture between the groups (OR = 1.19; 95% confidence interval, 0.80 to 1.78, p = 0.40). Adjustment for important covariates did not materially change these findings (OR = 1.17; 95% CI, 0.78 to 1.75). Comparing the rate of hip fracture between those women who regularly wore the devices and the control group yielded an OR of 1.12 (95% CI, 0.58 to 2.03; p = 0.83). This study is the largest RCT of hip protectors to date and provides no evidence of an effect of hip protectors among women living independently and at high risk of fracture.
    Osteoporosis International 10/2004; 15(9):701-6. · 4.04 Impact Factor
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    ABSTRACT: Common clinical risk factors for fracture in older women have been identified. To date, most of these risk factors have not been confirmed in a UK population. To confirm the important risk factors for fracture in older women. Comprehensive cohort study (CCS) with a nested randomized controlled trial. The CCS included 4292 women aged >70 years. We assessed potential risk factors for fracture, and followed-up participants for 24 months for incidence of non-vertebral fractures. Odds ratios (ORs) for predicting any non-vertebral fracture were: previous fracture, 2.67 (95%CI 2.10-3.40); a fall in the last 12 months, 2.06 (95%CI 1.63-2.59); and age (per year increase), 1.03 (95%CI 1.01-1.05). ORs for predicting hip fracture were: previous fracture, 2.31 (95%CI 1.31-4.08); low body weight (<58 kg), 2.20 (95%CI 1.28-3.77); maternal history of hip fracture, 1.68 (95%CI 0.85-3.31); a fall in the last 12 months, 2.92 (95%CI 1.70-5.01); and age (per year increase), 1.09 (95%CI 1.04-1.13). ORs for predicting wrist fracture were: previous fracture, 2.29 (95%CI 1.56-3.34); and a fall in the last 12 months, 1.60 (95%CI 1.10-2.31). Being a current smoker was not associated with an increase in risk, and was consistent across all fracture types. Older women with the clinical risk factors identified in this study should be investigated for osteoporosis or offered preventive treatment.
    QJM: monthly journal of the Association of Physicians 09/2004; 97(9):569-74. · 2.36 Impact Factor
  • Jill Porthouse, David J Torgerson
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    ABSTRACT: The randomized controlled trial is the most robust method available to evaluate health-care treatments. If podiatric medical practice is to be based on rigorous evidence, then high-quality randomized controlled trials are needed to inform that practice. In this article, we examine the extent to which randomized controlled trials are used in recent podiatric medical research and appraise the quality of those that are available. Using the Cochrane database of all randomized controlled trials in health care, we found only six relevant trials undertaken in podiatric medicine since 1997. These studies were of variable quality. We also discuss the key features of a rigorous trial design. To date, the clinical practice of podiatric medicine is not adequately informed by the best available evidence. We call for more high-quality randomized controlled trials to be undertaken in podiatric medical research.
    Journal of the American Podiatric Medical Association 05/2004; 94(3):221-8. · 0.77 Impact Factor
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    04/2004;
  • Yvonne Birks, Jill Porthouse, David J Torgerson
    Osteoporosis International 11/2003; 14(10):868-9; author reply 870. · 4.04 Impact Factor
  • Carole J. Torgerson, Jill Porthouse, Greg Brooks
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    ABSTRACT: This paper reports a systematic review of the trial literature in the field of adult literacy and numeracy. The review was undertaken to investigate the effectiveness of teaching strategies and pedagogies designed to increase adult literacy and numeracy. The objectives were to search for and locate, synthesise and quality appraise all the randomised controlled trials aiming to evaluate interventions in adult literacy and/or numeracy, published between 1980 and 2002. Fifty-nine papers were included in the descriptive map. Twelve papers were included that contained nine randomised controlled trials. All of the trials included in the review were of high quality in the sense that they had adopted an appropriate study design for assessing effectiveness. However, within that study design many of the studies had methodological problems, for example: small sample size and lack of justification of sample size calculation; unclear method of random allocation; high attrition rate and lack of ‘intention to teach’ analysis. There was evidence of publication bias. Pooling three studies that compared teaching against no teaching showed a strong, positive and statistically significant effect on outcome. Two other studies examined the use of computer-assisted instruction (CAI) on literacy among imprisoned adults. Pooling these two studies showed a modest but not statistically significant benefit. There is a dearth of rigorous RCTs in the field of adult literacy and numeracy. The evidence is suggestive of a benefit of adult literacy and numeracy interventions; however, because of the heterogeneity of studies, the precise role of any intervention is uncertain and this finding may be undermined by the presence of substantial publication bias. We recommend that a series of large, well-designed and well-conducted randomised trials should be undertaken in the field of adult literacy and numeracy.
    Journal of Research in Reading 09/2003; 26(3):234 - 255. · 1.25 Impact Factor
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    David Torgerson, Jill Porthouse
    BMJ (online) 05/2003; 326(7395):930; author reply 930. · 17.22 Impact Factor