Strategies to improve recruitment to research studies.

BACKGROUND: Research studies are essential to improving healthcare. However, many fail to recruit their planned number of participants. There are many interventions that researchers try to improve recruitment. Finding which ones are effective would be of benefit to the research community and society. OBJECTIVES: To quantify the effects of strategies to improve participation in research studies. SEARCH STRATEGY: We aimed to find all randomized and quasi-randomized controlled trials of strategies to improve recruitment to research studies. We searched nine electronic databases and manually searched the reference lists of relevant trials. We assessed the eligibility of each trial using pre-defined criteria. SELECTION CRITERIA: Randomized and quasi-randomized controlled trials of methods to increase recruitment in research studies. This includes non-healthcare studies. Studies that required only questionnaire completion were excluded. DATA COLLECTION AND ANALYSIS: We extracted data on the method evaluated, nature of the population, nature of the study to be recruited into, randomisation or quasi-randomisation method, allocation concealment, numbers and proportions in each arm. We used risk ratios and their 95% confidence intervals to describe the effects in individual trials, and assessed heterogeneity of these ratios between trials. MAIN RESULTS: We identified 15 eligible trials, including a total of 33,719 participants. All strategies were aimed at participants for healthcare studies. No strategies were identified at the level of researcher collaborators or ethics committees. Because of heterogeneity between trials and within strategies, the results were not synthesised. Trials of monetary incentives, an additional questionnaire at invitation and treatment information on the consent form demonstrated benefit; these specific interventions from individual trials are not easily generalizable. AUTHORS' CONCLUSIONS: On this evidence, it is not possible to predict the effect most interventions will have on recruitment. Funders and researchers should ensure that the evaluation of recruitment strategies are incorporated into research studies.

Interventions for increasing pedestrian and cyclist visibility for the prevention of death and injuries.

BACKGROUND: Pedestrians and cyclists account for nearly one in three of all road users killed and seriously injured in road traffic crashes. Late detection of other road users is one of the basic driver failures responsible for collisions. Aids to improve pedestrians and cyclist visibility have been used to avert potential collisions. However, the impact of these strategies on drivers' responses, and on pedestrian and cyclist safety is not known. OBJECTIVES: 1. To quantify the effect of visibility aids versus no visibility aids, and of different visibility aids on the occurrence of pedestrian and cyclist-motor vehicle collisions and injuries. 2. To quantify the effect of visibility aids versus no visibility aids, and of different visibility aids on drivers' detection and recognition responses. SEARCH STRATEGY: We searched the CENTRAL, the Cochrane Injuries Group specialised register, MEDLINE, TRANSPORT, National Research Register, PsycInfo and PsycLit. We searched the reference lists of included trials, contacted authors and searched the websites of relevant transport research organisations. The searches were last updated in April 2005. SELECTION CRITERIA: 1. Randomised controlled trials and controlled before-and-after studies of the effect of visibility aids on the occurrence of pedestrian and cyclist-motor collisions and injuries. 2. Randomised controlled trials of the effect of visibility aids on drivers' detection and recognition responses. This included trials where the order of presentation of visibility aids was randomised or balanced using a Latin square design. DATA COLLECTION AND ANALYSIS: Two authors independently screened records, extracted data and assessed trial quality. MAIN RESULTS: We found no trials assessing the effect of visibility aids on pedestrian and cyclist-motor vehicle collisions and injuries. We identified 39 trials assessing the effect of visibility aids on drivers' responses. Fluorescent materials in yellow, red and orange colours improve detection and recognition in the daytime. For night-time visibility, lamps, flashing lights and retroreflective materials in red and yellow colours increase detection and recognition. Retroreflective materials arranged in a 'biomotion' configuration also enhance recognition. Substantial heterogeneity between and within the trials limited the possibility for meta-analysis. Summary statistics and descriptive summaries of the outcomes were presented for individual trials when appropriate. AUTHORS' CONCLUSIONS: Visibility aids have the potential to increase visibility and enable drivers to detect pedestrians and cyclists earlier. Public acceptability of these strategies would merit further development. However, the effect of visibility aids on pedestrian and cyclist safety remains unknown. Studies which collect data on simple, meaningful outcomes are required.

Regulation of glucogenesis by thyroid hormones in fetal sheep during late gestation.

The effects of thyroid hormone deficiency in utero on the fetal glucogenic capacity were investigated by measuring glucose production and hepatic levels of glycogen and gluconeogenic enzymes in normal sheep fetuses in the fed and fasted states during late gestation and in those made thyroid hormone deficient by fetal thyroidectomy (TX). In the fed state, fetal TX had no effect on glucose uptake, utilisation or production by the fetus. It also had no apparent effect on the glycogen content or activities of the key gluconeogenic enzymes in the fetal liver. In addition, fetal plasma concentrations of insulin, cortisol, adrenaline or noradrenaline were unaffected by fetal TX in the fed state. In contrast, the rates of fetal O(2) consumption and CO(2) production per kilogram fetal bodyweight were significantly lower in TX than in intact fetuses in the fed state (P<0.05). TX prevented fetal glucose production in response to maternal fasting for 48 h. It also abolished the normal decreases in the fetal glucose carbon oxidation fraction, the rate of CO(2) production from glucose carbon and in the fraction of the umbilical O(2) uptake used for glucose carbon oxidation that occur during fasting in intact fetuses. At the end of the fast, plasma noradrenaline concentrations and hepatic levels of glycogen, glucose 6-phosphatase, fructose diphosphatase and alanine aminotransferase were significantly lower in TX than in intact fetuses. These observations show that thyroid hormones are essential for glucogenesis in the sheep fetus during late gestation and suggest that these hormones act both on the hepatic glucogenic pathways and on the mechanisms activating glucogenesis in utero.

High-frequency ventilation versus conventional ventilation for treatment of acute lung injury and acute respiratory distress syndrome.

BACKGROUND: High-frequency ventilation is often used to treat patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) but the effect of this treatment on clinical outcomes has not been well established. OBJECTIVES: The objective of this review is to examine the effect of high-frequency ventilation compared with conventional ventilation as a therapy for ALI or ARDS in children (1 to 17 years old) and adults in order to quantify its effect on patient outcome (mortality, morbidity and other relevant outcomes). SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, issue 4, 2002), MEDLINE (1966 to October Week 5, 2002), EMBASE (1980 to Week 51, 2002), World Wide Web (www.controlled-trials.com, ARDS clinical network), and used Cited Reference Search (Web of Science 1988 to 2002, for specific reference lists of articles). We also contacted authors from each included trial, as well as manufacturers of high-frequency ventilators and other researchers in the field. SELECTION CRITERIA: Randomized controlled clinical trials of children and adults comparing treatment using high-frequency ventilation with conventional ventilation for patients diagnosed with ALI or ARDS. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. MAIN RESULTS: Two trials met the inclusion criteria for this review. One trial recruited children (including some children less than one year old) (n = 58) and the other recruited adults (n = 148). Both trials used a high-frequency oscillatory ventilator as the intervention and included variable use of lung-volume recruitment strategies. The intervention groups showed a trend towards lower 30 day mortality (children relative risk (RR) 0.83, 95% confidence interval (CI) 0.43 to 1.62; adults RR 0.72, 95% CI 0.50 to 1.03), although neither study showed a statistically significant difference. Similarly, there was no statistically significant difference between the intervention and control groups for 'Total length of ventilator days' (WMD) -2.00, 95% CI -18.36 to 14.36; and WMD 2.00, 95% CI -6.55 to 10.55 for the child and adult trials respectively). The studies used only proxies to measure long-term quality of life. There was a statistically significant reduction in the risk of requiring supplemental oxygen amongst survivors at 30 days in the paediatric study (RR 0.36, 95% CI 0.14 to 0.93). REVIEWER'S CONCLUSIONS: There is not enough evidence to conclude whether high-frequency ventilation reduces mortality or long-term morbidity in patients with ALI or ARDS; further trials are needed.

Interventions for increasing pedestrian and cyclist visibility for the prevention of death and injuries.

BACKGROUND: Pedestrians and cyclists account for nearly one in three of all road users killed and seriously injured in road traffic crashes. Late detection of other road users is one of the basic driver failures responsible for collisions. Aids to improve pedestrians and cyclist visibility have been used to avert potential collisions. However, the impact of these strategies on drivers' responses, and on pedestrian and cyclist safety is not known. OBJECTIVES: 1. To quantify the effect of visibility aids vs no visibility aids, and of different visibility aids on the occurrence of pedestrian and cyclist-motor vehicle collisions and injuries. 2. To quantify the effect of visibility aids vs no visibility aids, and of different visibility aids on drivers' detection and recognition responses. SEARCH STRATEGY: We searched the Cochrane Controlled Trials Register, the Injuries Group Specialised Register, MEDLINE, TRANSPORT, TRANSDOC from ECMT (European Conference of Ministers of Transport), IRRD (International Road Research Documentation), TRIS (Transportation Research Information Services), NRR (National Research Register), PsycInfo and PsycLit. SELECTION CRITERIA: 1. Randomised controlled trials and controlled before/after trials of the effect of visibility aids on the occurrence of pedestrian and cyclist-motor collisions and injuries. 2. Randomised controlled trials of the effect of visibility aids on drivers' detection and recognition responses. This included trials where the order of presentation of visibility aids was randomised or balanced using a Latin square design. DATA COLLECTION AND ANALYSIS: Two reviewers independently screened records, extracted data and assessed trial quality. MAIN RESULTS: We found no trials assessing the effect of visibility aids on the occurrence of pedestrian and cyclist-motor vehicle collisions and injuries. We identified 37 trials assessing the effect of visibility aids on drivers' responses. Fluorescent materials in yellow, red and orange colours improve detection and recognition in the daytime. For night-time visibility, lamps, flashing lights and retroreflective materials in red and yellow colours increase detection and recognition. Retroreflective materials arranged in a 'biomotion' configuration also enhance recognition. Substantial heterogeneity between and within the trials limited the possibility for meta-analysis. Summary statistics and descriptive summaries of the outcomes were presented for individual trials when appropriate. REVIEWER'S CONCLUSIONS: Visibility aids have the potential to increase visibility and enable drivers to detect pedestrians and cyclists earlier. Public acceptability of these strategies would merit further development. However, the effect of visibility aids on pedestrian and cyclist safety remains unknown. Studies which collect data on simple, meaningful outcomes are required.