Plasma lycopene concentrations in humans are determined by lycopene intake, plasma cholesterol concentrations and selected demographic factors.
(33/12901)
Higher plasma lycopene concentrations have been associated with a reduced risk of several chronic diseases. Determinants of lycopene concentrations in humans have received limited attention. We had blood lycopene concentrations and lycopene consumption data available from 111 participants in a two-center cancer prevention trial involving beta-carotene and examined determinants of plasma lycopene levels cross-sectionally. The median plasma lycopene level was 0.59 micromol/L (range 0.07-1.79). Low plasma concentrations of lycopene were associated with the following variables in univariate analyses: study site (Florida lower than Connecticut, P = 0.001), being nonmarried (P = 0.02), having lower income (P = 0.003), being nonwhite race/ethnicity (P = 0.03), having lower dietary lycopene intake (r = 0.29, P = 0.002), having lower plasma cholesterol (r = 0. 43, P = 0.0001) and triglyceride levels (r = 0.26, P = 0.005), and consuming less vitamin C (r = 0.20, P = 0.03). Women had slightly higher plasma lycopene levels than men (0.65 vs. 0.58 micromol/L; P = 0.31), despite lower dietary intake of lycopene (1,040 vs. 1,320 microg/d; P = 0.50). Plasma lycopene levels did not differ in smokers and nonsmokers. In stepwise regression analyses, the determinants of plasma lycopene were plasma cholesterol, dietary lycopene, and marital status; these three variables explained 26% of the variance in plasma lycopene. Relatively few lifestyle and demographic factors were important determinants of plasma lycopene levels, with plasma cholesterol, marital status, and lycopene intake being of greatest importance. (+info)
Evaluation of screening for nasopharyngeal carcinoma: trial design using Markov chain models.
(34/12901)
In this paper, we develop a Markov chain model to estimate parameters pertaining to the natural history of nasopharyngeal carcinoma (NPC). The model is of progression from no disease to Epstein-Barr virus (EBV) infection, preclinical screen-detectable tumour and clinical tumour. We derive tentative estimates of the parameters of the model, based on limited published data, to assess the efficacy of serum screening in conjunction with clinical assessment (indirect mirror examination for NPC), for example the average duration of the preclinical screen-detectable phase is estimated as 3.1 years. We further apply these parameters to a hypothetical screening trial in the Hong Kong population to assess the efficacy of serum screening with clinical assessment by different combinations of screening regime. Results suggest: (1) there is no substantial difference between 3-yearly and 6-yearly serum screening; and (2) within the same serum screening regime annual and 3-yearly clinical assessment can prevent 33% and 28% of deaths from NPC respectively. Prediction of deaths and surrogate end points can be used to estimate the required sample size and duration for designing a randomized trial of screening for NPC. Based on these findings and power projections, we suggest a design for a randomized trial in a high incidence area such as Hong Kong. (+info)
Systematic review of antistaphylococcal antibiotic therapy in cystic fibrosis.
(35/12901)
BACKGROUND: The respiratory tract in patients with cystic fibrosis is frequently colonised with Staphylococcus aureus. There is great diversity of clinical practice in this area of cystic fibrosis. A systematic review was conducted to study the evidence relating antistaphylococcal therapy to clinical outcome in patients with cystic fibrosis. METHODS: A search strategy already evaluated for the study of the epidemiology of cystic fibrosis clinical trials was used. This yielded 3188 references from which 13 clinical trials of antistaphylococcal therapy were identified. RESULTS: Substantial heterogeneity was observed between trials. In the 13 clinical trials a total of 19 antibiotics were used to assess a wide variety of outcome measures (11 clinical, six laboratory). Both intermittent and continuous treatment strategies were used. Sputum clearance of S aureus was more frequently achieved than any other beneficial outcome. A beneficial effect on pulmonary function was rarely measured or observed. Although five randomised clinical trials were identified, the extent of heterogeneity precluded the use of meta-analysis for further synthesis of information. CONCLUSIONS: Antistaphylococcal treatment achieves sputum clearance of S aureus in patients with cystic fibrosis. Prophylactic antistaphylococcal treatment in young children with cystic fibrosis is likely to be of clinical benefit. It remains to be determined whether the use of "prophylactic" versus "intermittent" antistaphylococcal therapy in cystic fibrosis is associated with improved lung function and/or chest radiographic scores, an increase in bacterial resistance, or earlier acquisition of Pseudomonas aeruginosa. A large randomised clinical trial lasting approximately two years is urgently required to address this problem. (+info)
Tacrolimus versus cyclosporin for immunosuppression in renal transplantation: meta-analysis of randomised trials.
(36/12901)
OBJECTIVE: To compare tacrolimus with cyclosporin for immunosuppression in renal transplantation. DESIGN: Meta-analysis of randomised trials of two treatments after kidney transplantation. IDENTIFICATION: Four studies involving 1037 patients. Trials were included if they were randomised, the intervention group received tacrolimus, the control group received cyclosporin, the patients were followed for a minimum of 12 months, and patient survival, graft survival, incidence of acute rejection, need for antilymphocyte treatment, or the prevalence of diabetes mellitus after transplant was reported. MAIN OUTCOME MEASURES: Pooled estimates of patient mortality, allograft loss, and episodes of acute rejection 1 year after transplantation. RESULTS: The odds ratio for loss of allograft with tacrolimus compared with cyclosporin was 0.95 (95% confidence interval 0.65 to 1.40). The odds ratio for mortality with tacrolimus was 1.07 (0.47 to 2.48). Treatment with tacrolimus was associated with a reduction in episodes of acute rejection (0.52; 0.36 to 0.75), a reduction in the use of antilymphocyte antibodies to treat rejection (0.37; 0.25 to 0. 56), and an increased prevalence of diabetes mellitus after transplantation (5.03; 2.04 to 12.36) compared with treatment with cyclosporin. CONCLUSIONS: After renal transplantation, immunosuppression with tacrolimus results in a significant reduction in acute rejection compared with cyclosporin. Follow up studies of high methodological quality are needed to determine whether tacrolimus improves long term renal graft survival. (+info)
Is recruitment more difficult with a placebo arm in randomised controlled trials? A quasirandomised, interview based study.
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OBJECTIVE: To investigate whether including a placebo arm in a clinical trial of hormone replacement therapy influenced women's stated willingness to participate. DESIGN: Quasirandomised, interview based study. SETTING: 10 group practices in the Medical Research Council's General Practice Research Framework. PARTICIPANTS: 436 postmenopausal women aged 45-64 who had not had a hysterectomy. MAIN OUTCOME MEASURES: Stated willingness to enter a trial and reasons for the decisions made. RESULTS: Of 218 women told about the trial without a placebo arm, 85 (39%) indicated their willingness to enter compared with 65 (30%) of the 218 women told about the trial with the placebo arm (P=0.06). Part of this difference was due to explicit reluctance to take a placebo. Altruism and personal benefit were the reasons most frequently given for wanting to take part in a trial. The reasons most frequently cited for not wanting to take part were reluctance to restart periods, not wanting to take unknown or unnecessary tablets, or not wanting to interfere with present good health. CONCLUSION: For preventive trials the inclusion of a placebo arm may reduce patients' willingness to participate. (+info)
Short-course therapy of acute cystitis: a brief review of therapeutic strategies.
(38/12901)
Acute cystitis is one of the commonest medical problems encountered by primary care physicians. It affects more women than men (8:1), but the incidence among men is increasing. Uncomplicated cystitis by definition occurs in healthy patients with a normal urinary tract, whereas complicated cystitis implies a predisposing or underlying condition. A narrow range of aetiological agents is responsible for most uncomplicated cystitis in women (Escherichia coli in 80% of cases). Recently, however, pathogens usually associated with sexually transmitted disease have been implicated. In women with typical symptoms of acute uncomplicated cystitis, an abbreviated laboratory work-up followed by empirical therapy is recommended. Single-dose and 3 day regimens of co-trimoxazole and the quinolones are as effective as longer regimens and have a higher eradication rate than other commonly used antimicrobials. Relapse rates are slightly higher with single-dose therapy. With this success rate plus the reduced cost and improved patient compliance, these regimens have replaced traditional 5 to 14 day courses of treatment. With increasing resistance of the common urinary pathogens to amoxycillin and, now, co-trimoxazole, the quinolones are a logical choice for empirical therapy of uncomplicated urinary tract infections. (+info)
A search for the evidence supporting community paediatric practice.
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AIM: Controversy exists regarding the evidence base of medicine. Estimates range from 20% to 80% in various specialties, but there have been no studies in paediatrics. The aim of this study was to ascertain the evidence base for community paediatrics. METHODS: Twelve community paediatricians working in clinics and schools in Yorkshire, Manchester, Teesside, and Cheshire carried out a prospective review of consecutive clinical contacts. Evidence for diagnostic processes, prescribing, referrals, counselling/advice, and child health promotion was found by searching electronic databases. This information was critically appraised and a consensus was obtained regarding quality and whether it supported actions taken. RESULTS: Two hundred and forty-seven consultations and 1149 clinical actions were performed. Good evidence was found from a randomised controlled trial or other appropriate study for 39.9% of the 629 actions studied; convincing non-experimental evidence for 7%; inconclusive evidence for 25.4%; evidence of ineffectiveness for 0.2%; and no evidence for 27.5%. Prescribing and child health promotion activities had the highest levels of quality evidence, and counselling/advice had the lowest. CONCLUSIONS: An encouraging amount of evidence was found to support much of community paediatric practice. This study improved on previous research in other specialties because actions other than medications and surgery were included. (+info)
Meta-analysis of elective high frequency ventilation in preterm infants with respiratory distress syndrome.
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AIM: To summarise the evidence on the efficacy of elective high frequency ventilation compared with conventional ventilation in preterm infants with respiratory distress syndrome. METHODS: A search from 1987 onwards was made on Embase, Medline, and the Cochrane Library. A questionnaire was also circulated during an international meeting on high frequency ventilation. To be included in the data synthesis, studies had to be randomised controlled trials comparing elective high frequency ventilation with conventional ventilation in preterm infants with respiratory failure due to respiratory distress syndrome; indices of mortality, chronic pulmonary morbidity, and other clinically relevant outcomes were compared. Studies were assessed for methodological validity according to explicit criteria. RESULTS: Ten studies (a total number of 1345 preterm infants) were considered for data synthesis. No difference in mortality at 28 or 30 days, nor in oxygen dependency at 28 days was found between both types of ventilation. Reduced oxygen dependency at the postconceptional age of 36 weeks (RR 0.50, 95% CI 0.32-0.78) was found, but so was an increase in grades 3 and 4 intraventricular haemorrhage (IVH) (RR 1.31, 95% CI 1.04-1.66). Those studies using a high lung volume ventilatory strategy showed a significant decrease in oxygen dependency at the postconceptional age of 36 weeks (RR 0.44, 95% CI 0.27-0.73), but no increase in severe IVH (RR 0.78, 95% CI 0.45-1.37). CONCLUSIONS: Although high frequency ventilation reduces chronic lung disease, it seems to increase the risk of severe IVH. These results are dominated by an early study where the absence of benefit on pulmonary outcomes, and the increase in adverse neurological events, could be related to the low volume ventilatory strategy used. Recent studies, using a high lung volume approach, show better pulmonary outcomes without any increase in intracranial morbidity. Still, uncertainty remains about long term pulmonary and neurodevelopmental outcome. (+info)