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PubMed2000

Evidence of clinical efficacy of homeopathy. A meta-analysis of clinical trials. HMRAG. Homeopathic Medicines Research Advisory Group.

OBJECTIVE: To establish, using a systematic review and meta-analysis, whether there is any evidence from randomised controlled clinical trials of the efficacy of homeopathic treatment in patients with any disease. DATA SOURCES: Published and unpublished reports of controlled clinical trials available up to June 1998, identified by searching bibliographic databases (Medline, Embase, Biosis, PsychInfo, Cinahl, British Library Stock Alert Service, SIGLE, Amed), references lists of selected papers, hand searching homeopathic journals and conference abstracts, and contacting pharmaceutical companies. TRIALS SELECTION: Trials were selected using an unblinded process by two reviewers. The selection criteria were randomised, controlled trials in which the efficacy of homeopathic treatment was assessed relative to placebo in patients using clinical or surrogate endpoints. Prevention trials or those evaluating only biological effects were excluded. One hundred and eighteen randomised trials were identified and evaluated for inclusion. Sixteen trials, representing 17 comparisons and including a total of 2,617 evaluated patients, fulfilled the inclusion criteria. DATA EXTRACTION: Data were extracted by two reviewers independently, using a summary form. Disagreements were resolved by a third person. DATA SYNTHESIS: The evidence was synthesised by combining the significance levels (P values) for the primary outcomes from the individual trials. The combined P value for the 17 comparisons was highly significant P = 0.000036. However, sensitivity analysis showed that the P value tended towards a non-significant value (P = 0.08) as trials were excluded in a stepwise manner based on their level of quality. CONCLUSIONS: There is some evidence that homeopathic treatments are more effective than placebo; however, the strength of this evidence is low because of the low methodological quality of the trials. Studies of high methodological quality were more likely to be negative than the lower quality studies. Further high quality studies are needed to confirm these results.

Homeopathy↗
PubMed2005

A single-use site selection technique, using GIS, for aquaculture planning: choosing locations for mangrove oyster raft culture in Margarita Island, Venezuela.

Oyster culture has a potential to generate income for coastal communities and to lessen pressure on natural overexploited populations. A project to transfer mangrove oyster Crassostrea rhizophorae raft culture technology to selected coastal communities in Margarita Island, Venezuela is being developed, and an optimum location selection technique was devised. To pick the variables or factors that determine site suitability, a bibliographic database was made, aspects of interest chosen, and the most comprehensive ones singled out, eliminating redundant ones. Twenty variables were grouped in criteria based on the way they influence the project. Variables were classified as intrinsic environmental, environmental extrinsic, logistic, and socioeconomic criteria. Thirty-five experts were asked to evaluate the factors and to score each according to their suitability weight. Logistic criterion received the highest values, followed by environmental extrinsic issues. A Geographic Information System using a base map compiled from 1:25,000 scale maps was developed. A thematic map for each factor was completed, dividing graphically the 3896-km2 study area into polygons of equal weight for each factor. The Multi-Criteria Evaluation (MCE) was used to combine the variables. Resultant vectors in thematic maps were added to obtain smaller polygons with the same value sum. Finally, MCE was used to generate a final output: the optimum sites for oyster aquaculture resulting from the added values of over 3000 polygons in the maps, for the 20 criteria. Higher scores were reached in 13 areas covering 4.1 km2, those places having the optimum conditions for oyster raft aquaculture in the region. Additional locations meeting 75% to 70% of the demanded criteria for a final suitable selection cover 137 sites encompassing 37.5 km2.

Animals↗
PubMed1998

Evidence-based operations in paediatric surgery.

It has been assumed that only 10% of medical interventions are supported by solid scientific evidence. The aim of this study was to determine the type of research evidence supporting operations in a tertiary referral paediatric surgical unit. All patients admitted over a 4-week period to two surgical firms were enrolled in the study. All major operations carried out on each patient since birth were evaluated. Patients for whom a diagnosis was not reached were excluded. A bibliographic database (MEDLINE) was used to search for the articles published between January 1986 and December 1995 on the analysed operations. The type of evidence supporting the operations was classified as follows: I=evidence from randomised controlled trials (RCTs); II=self-evident intervention (obvious effectiveness not requiring RCTs); III=evidence from prospective and/or comparative studies; IV=evidence from follow-up studies and/or retrospective case series; and V=intervention without substantial evidence for or against results of randomised trials. Seventy operations (32 individual types) were performed on 49 patients (1-5 operations/patient); 18 (26%) were supported by RCTs (type of evidence I). Two patients (3%) received a self-evident intervention (type II); 48 operations (68%) were based on non-randomised prospective or retrospective studies (type III=13%; type IV=55%). Two patients (3%) received an operation not supported by or against convincing scientific evidence (type V). A significant proportion of operations in paediatric surgery is supported by RCTs. However, the vast majority of these trials were conducted on adult patients. Sixty-eight per cent of the operations were based on prospective follow-up studies or retrospective case series, which may not represent solid scientific evidence. More RCTs are needed in paediatric surgery.

Child↗
PubMed1997

[Systematic reviews in cardiology: approaches to evidence-based medicine and the Cochrane Collaboration].

The ever growing tide of results from great numbers of clinical studies clearly outweighs the abilities of the individual clinician to keep abreast of the actual state of scientific evidence and to apply it in his clinical decision-making in a timely and valid manner. Evidence-based medicine, with its central demand to link best individual clinical knowledge with best available external, scientific evidence to achieve optimal patient care, has clearly identified the urgent need for scientific techniques which allow the synthesis of scientific evidence, as collected in numerous singular studies, in an explicit, reproducible, and critically appraisable report format, and to update these reports regularly. The methods of Systematic Reviews, encompassing the techniques of meta-analysis, were developed for this purpose. They are explained and presented here in detail as they relate to the field of cardiology. Various problematic aspects have recently dominated cardiologists' discussion of meta-analyses. We point out that the techniques of Systematic Reviews hold promising solutions for many of them and that work on technical improvements is ongoing. The International Cochrane Collaboration is introduced as a global network of scientists and experts from varying fields of medicine with the aim of producing highest quality Systematic Reviews on a wide scope of topics. However, to date only few cardiologists have joined the rapidly rising numbers of Cochrane collaborators.

Cardiology↗
PubMed2004

Botulinum toxin in the treatment of rare head and neck pain syndromes: a systematic review of the literature.

BACKGROUND: Botulinum neurotoxin (BoNT) is used to treat various neurological disorders associated with pathologically increased muscle tone. Botulinum toxin inhibits the release of the neurotransmitter acetylcholine at the neuromuscular junction thereby inhibiting striatal muscle contractions. Besides the reduction in muscle tone BoNT tends to reduce pain in pain syndromes associated with muscle spasm. In addition, BoNT has been proposed as an analgesic, suggesting alternative non-cholinergic mechanisms of action.Surprisingly, BoNT was reported as a potential treatment for tension-type headache and migraine-both primary headache syndromes without an apparent muscular component-however, varying responses to BoNT have been found, overall without sufficient evidence for a general treatment. In this systematic review we set out to clarify the efficacy and safety of BoNT in the treatment of rare head and neck pain syndromes (e. g. cervicogenic headache, chronic paroxysmal hemicrania, cluster headache, trigeminal neuralgia, temporomandibular disorders, cervical dystonia and whiplash injuries). OBJECTIVES: To assess the analgesic efficacy and safety of botulinum toxins versus other medicines, placebo or no treatment in rare head and neck pain syndromes. SEARCH STRATEGY: We searched the bibliographic databases MEDLINE, EMBASE and PASCAL Biomed to May 2003. We also reviewed the reference lists from identified articles including reviews and meta-analyses of treatment studies. Furthermore we searched booklets of scientific congresses in the field of neurology for potentially relevant studies. Additional reports were identified from the reference list of the retrieved papers, and by contacting experts in the field. SELECTION CRITERIA: Randomized controlled trials (RCTs) with any dose of BoNT for rare head and neck pain syndromes, describing subjective pain assessment as either the primary or a secondary outcome, were included in this review. DATA COLLECTION AND ANALYSIS: All trials were quality scored and two independent reviewers extracted data. Results were compared for differences, and discrepancies were resolved by discussion. MAIN RESULTS: Fourteen RCTs of BoNT in cervical dystonia were included in this review. All except one showed significant pain relief following BoNT treatment compared to placebo. Studies providing dichotomous outcome data were pooled using the Peto method. The overall effect was found to be highly significant (OR 4.795 [95% CI 5.551-6.473]). For cervicogenic headache, two RCTs-one positive study and one negative study-were included. Two studies addressing chronic neck pain were included in this review. Both studies did not reveal significant effects. Furthermore, one small trial (N = 15 patients) focussing BoNT in temporomandibular disorders was included,without demonstrating significant effectiveness but a high proportion of patients lost to follow-up and a high rate of adverse effects. For the use of BoNT in cluster headache, chronic paroxysmal hemicrania and trigeminal neuralgia no RCTs were identified. Adverse effects (AEs) were found to be mild to moderate and dose-dependent. They were summarized where possible, irrespective of the formulation used and condition treated (OR = 5.066 [95% CI 2.770-9.265], number-needed-to-harm (NNH) = 5.5 [range 4.4-17]). REVIEWERS' CONCLUSIONS: There is convincing evidence for the effectiveness of BoNT in the treatment of pain associated with cervical dystonia. Due to the frequent adverse effects predominantly observed with higher doses, the trade off in risk and benefit should be carefully considered in each case. For all other rare head and neck pain syndromes we found no RCTs (cluster headache, chronic paroxysmal hemicrania, trigeminal neuralgia) and only a few small sized trials (cervicogenic headache, chronic neck pain, temporomandibular disorders). We were therefore unable to draw any definite conclusions.

Anti-Dyskinesia Agents↗
PubMed2003

["Facial pain" in German-language medical textbooks on pain (1990-2002)].

INTRODUCTION: The aim of this study was to determine how frequently and to what extent facial pain--particularly musculoskeletal and neuropathic pain--has been considered in German-language textbooks on pain published between 1990 and 2002. METHODS: Relevant textbooks were identified by hand search and by search in electronic bibliographic databases. A quantitative analysis was carried out by counting and comparing the number of pertinent pages in the textbooks. For the assessment of the medical-scientific quality of the information on musculoskeletal face pain, a checklist was used based on comparisons with the current state of the scientific literature on facial pain. RESULTS: Of 231 textbooks on pain, 28 consider the topic of "facial pain." Of the 1923 pages dedicated to facial pain and headache, musculoskeletal and neuropathic facial pain make up 7% and 17%, respectively. Headache, in contrast, accounts for 71% of all pages. Only ten contributions on musculoskeletal facial pain could be assessed, two of which exhibit a high medical-scientific quality. CONCLUSIONS: The data suggest that facial pain is underrepresented in German-language textbooks on pain. In addition, a considerable part of the information given on musculoskeletal facial pain does not correspond to the current state of the scientific literature. This may lead to under- or overdiagnosis and to under- or overtreatment.

Facial Pain↗
PubMed2004

Tumors associated with sudden infant and childhood death.

Tumors are rare causes of sudden death in infancy and early childhood. The goals of this study were to determine the types and frequency of the tumors associated with sudden death occurring in cases between birth and age 3 years. The San Diego Sudden Infant Death Syndrome/sudden unexplained death in childhood (SUDC) Research Project database and the literature were reviewed retrospectively. Sixty-eight cases, with the most (84%) affecting the heart and brain, were identified. Tumors are a rare but significant cause of sudden death in infancy and early childhood, and their diagnosis may have significant genetic implications for planning future pregnancies. The diagnosis of these lesions can be established only after thorough postmortem examination.

California↗
PubMed2006

Duplicate publication and 'paper inflation' in the Fractals literature.

The similarity of documents in a large database of published Fractals articles was examined for redundancy. Three different text matching techniques were used on published Abstracts to identify redundancy candidates, and predictions were verified by reading full text versions of the redundancy candidate articles. A small fraction of the total articles in the database was judged to be redundant. This was viewed as a lower limit, because it excluded cases where the concepts remained the same, but the text was altered substantially. Far more pervasive than redundant publications were publications that did not violate the letter of redundancy but rather violated the spirit of redundancy. There appeared to be widespread publication maximization strategies. Studies that resulted in one comprehensive paper decades ago now result in multiple papers that focus on one major problem, but are differentiated by parameter ranges, or other stratifying variables. This 'paper inflation' is due in large part to the increasing use of metrics (publications, patents, citations, etc) to evaluate research performance, and the researchers' motivation to maximize the metrics.

Algorithms↗
PubMed1991

Health care data, the epidemiologist's sand: comments on the quantity and quality of data.

Massive amounts of health care data are currently available for epidemiologic review through improvements in computerization and electronic communication. Multiple abstracts of patient care data are collected, stored, retrieved, and analyzed to study health care practice and outcome. The high level of variation in data from these sources is noted. Examples of these data collections are reviewed and the issues of the quality of these data for research and evaluation are discussed. Increased amounts of poor quality data will not be helpful. Collections from the National Center for Health Statistics and other sources are cited as models for improved standards for quality data banks and registries, including the Centers for Disease Control National Nosocomial Infections Surveillance collection. Throughout, a metaphor relating quality of sand for the production of lens instruments to view scientific change is used.

Data Collection↗
PubMedDate not supplied

Molecular biological databases--present and future.

The importance of databases as a research tool in molecular biology is growing steadily, and a wide range of databases relevant to genome research is currently available. However, the design of current databases is inadequate for accurate representation and analysis of the results of large-scale genome mapping and sequencing projects. A new generation of databases is required to master the challenges of the future.

Animals↗
PubMedDate not supplied

From data banks to data bases.

The information collected in national and international libraries on nucleotide and protein sequences cannot be directly treated for proper handling by existing software. Therefore we evaluated the feasibility of constructing a data base for Escherichia coli using the data present in the banks. The knowhow thus acquired was applied to Bacillus subtilis. Specific examples of the general procedure are given.

Bacillus subtilis↗
PubMed2004

Firearm ownership and storage practices, U.S. households, 1992-2002. A systematic review.

BACKGROUND: Because the presence and improper storage of household firearms are risk factors for injury, it is important to understand the prevalence of ownership and storage practices within households to help guide intervention development. This systematic review of published articles (1992 to 2002) provides prevalence estimates of firearm ownership and storage practices in U.S. households. METHODS: A search of bibliographic databases (MedLine, CINAHL, PsycInfo, Sociological Abstracts) was completed in January 2003. RESULTS: Although all were cross-sectional, the 42 articles included in this review varied in type; there were seven national and five state prevalence studies, as well as studies using clinic-based convenience samples (n =14) and samples of professionals (n =10). Published studies indicate that firearms are present in about one third of U.S. households. Handguns in particular are present in more than half of U.S. households with firearms, or about 19% of all U.S. households. The prevalence of firearms and handguns in households with young people was similar to the prevalence overall. Firearm ownership was highest in the South. CONCLUSIONS: Although the methodologic rigor of published articles varies substantially, the literature clearly establishes that firearms are common in U.S. households, even in the homes of medical professionals and those with children.

Adolescent↗
PubMed2005

Long-term effectiveness of weight-loss interventions in adults with pre-diabetes: a review.

OBJECTIVE: To assess the effectiveness of weight-loss and weight-control interventions for adults with pre-diabetes (impaired fasting glucose and impaired glucose tolerance), an important risk factor for the development of type 2 diabetes. METHODS: Computerized searches were conducted of multiple electronic bibliographic databases up to August 2003. Randomized controlled trials in any language were selected that examined weight-loss or weight-control strategies using at least one dietary, physical activity, or behavioral intervention, and with a follow-up interval of a per thousand yen12 months. Effects were combined using a random effects model. RESULTS: Studies were identified, with a total of 5168 participants. Follow-up ranged from 1 to 10 years. Quantitative synthesis was limited by the heterogeneity of populations, settings, and interventions, and by the small number of studies that examined outcomes other than weight. Overall, compared to usual care, four studies with a follow-up of 1 year reduced weight by 2.8 kg (95% confidence interval [CI]=1.0-4.7) (3.3% of baseline body weight) and decreased body mass index by 1.4 kg/m(2) (CI=0.5-2.3). Weight loss at 2 years was 2.7 kg (CI=1.9-3.4) (two studies). Modest improvements were noted in the few studies that examined glycemic control, blood pressure, and lipid concentrations (p >0.05). The incidence of diabetes was significantly lower in the intervention groups versus the controls in three of five studies examining this outcome at 3 to 6 years follow-up. CONCLUSIONS: Overall, weight-loss strategies using dietary, physical activity, or behavioral interventions produced significant improvements in weight among persons with pre-diabetes, and a significant decrease in diabetes incidence. Further work is needed on the long-term effects of these interventions on morbidity and mortality and on how to implement these interventions in the community setting.

Adult↗
PubMed2005

Acculturation and smoking patterns among Hispanics: a review.

OBJECTIVE: To conduct a systematic review of published studies investigating the association of acculturation and smoking patterns among Hispanic men and women in the United States. METHODS: Online bibliographic databases were searched from 1985 to 2003 using three key search terms. The methodology and findings of all retrieved articles were critically evaluated. Data were extracted from each article regarding study population, study methods, exposure assessment, outcomes measured, acculturation measures used, and results. RESULTS: The literature search identified 78 articles from MEDLINE, PubMed, and PsychINFO databases; of these, 11 studies met the inclusion criteria. Seven regional studies based in the western United States and four nationwide studies were included in the review. Seven studies used formal acculturation scales, three used language spoken, and one used language spoken and country of birth to indicate acculturation status. Nine studies showed a positive association between acculturation and smoking among women, and one study involving men showed a negative association. CONCLUSIONS: The findings suggest that the association of acculturation and smoking is gender-specific. In this instance, increased smoking prevalence with increased acculturation is consistently observed among Hispanic women but not among men. As Hispanic women acculturate, their cigarette smoking may increase because their behavior becomes more strongly influenced by the norms and practices of the dominant group than among men. Immigrant- and gender-specific public health interventions need to be designed to combat the increase in smoking rates among Hispanics in the United States.

Acculturation↗
PubMed2004

Long-term effectiveness of lifestyle and behavioral weight loss interventions in adults with type 2 diabetes: a meta-analysis.

BACKGROUND: Most persons with type 2 diabetes are overweight, and obesity worsens the metabolic and physiologic abnormalities associated with diabetes. Our objective was to assess the effectiveness of lifestyle and behavioral weight loss and weight control interventions in adults with type 2 diabetes. METHODS: Studies were obtained from searches of multiple electronic bibliographic databases, supplemented with hand searches of selected journals and consultation with experts in obesity research. Studies were included if they were published or unpublished randomized controlled trials in any language that examined weight loss or weight control strategies using one or more dietary, physical activity, or behavioral interventions, with a follow-up interval of at least 12 months. Effects were combined using a random-effects model. RESULTS: The 22 studies of weight loss interventions identified yielded a total of 4659 participants with a follow-up of 1 to 5 years. The pooled weight loss for any intervention in comparison with usual care among 585 subjects was 1.7 kg (95% confidence interval [CI]: 0.3 to 3.2 kg), or 3.1% of baseline body weight among 511 subjects. Among 126 persons who underwent a physical activity and behavioral intervention, those who also received a very low-calorie diet lost 3.0 kg (95% CI: -0.5 to 6.4 kg), or 1.6% of baseline body weight, more than persons who received a low-calorie diet. Among 53 persons who received identical dietary and behavioral interventions, those who received a more intense physical activity intervention lost 3.9 kg (95% CI: -1.9 to 9.7 kg), or 3.6% of baseline body weight, more than those who received a less intense or no physical activity intervention. Comparison groups often achieved substantial weight loss (up to 10.0 kg), minimizing between-group differences. Changes in glycated hemoglobin level generally corresponded to changes in weight and were not substantial when between-group differences were examined. CONCLUSION: Weight loss strategies involving dietary, physical activity, or behavioral interventions were associated with small between-group improvements in weight. These results were minimized by weight loss in the comparison group, however, and examination of individual study arms revealed that multicomponent interventions, including very low-calorie diets or low-calorie diets, may hold promise for achieving weight loss in adults with type 2 diabetes.

Behavior Therapy↗
PubMed2006

Economic value of out-of-hospital emergency care: a structured literature review.

STUDY OBJECTIVE: The evaluation of the impact of out-of-hospital emergency care is a relatively new research focus. As such, there is a compelling need to determine how finite health care resources should be used in this setting. The objective of this study is to conduct a structured review of published economic evaluations of out-of-hospital emergency care to assess its economic value. METHODS: A structured literature search and structured review of articles pertaining to the economic value of out-of-hospital care was performed. The bibliographic database MEDLINE was searched for pertinent English-language articles published between 1966 and 2003. The search used the medical subject headings "emergency medical services" and "emergency medical technician" and was limited to the subheading "economics" and crossed with the medical subject heading "economics." The titles generated by this search were systematically reviewed and limited by topic. Abstracts from the identified titles were reviewed to select a final set of pertinent articles. These articles were further limited based on explicit inclusion and exclusion criteria. Authors used a previously published structured evaluation tool to review the final set of identified articles for quality and content. RESULTS: The initial MEDLINE search identified 3,533 citations. From this set, 535 potentially relevant abstracts were reviewed. From the abstract review, 46 articles were identified, along with an additional 14 from searching the secondary references. Of these 60 articles, 32 met the review inclusion criteria and were subjected to a full structured review. These studies predominantly addressed the cost of cardiac arrest (n=13, 41%), major trauma (n=8, 25%), and emergency medical services treatment in general (n=8, 25%). Only 14 studies considered the costs and consequences of competing alternatives. Of these, 2 were cost-benefit and 12 were cost-effectiveness evaluations. Two of the 14 studies met all 10 criteria for high-quality economic evaluation, whereas 2 others met none. CONCLUSION: There is a paucity of out-of-hospital care literature that addresses cost and economic value. The extant literature is limited in scope, poor in quality, and evaluates small subsets of out-of-hospital emergency care costs. Favorable cost-effectiveness has not been firmly established for most aspects of out-of-hospital emergency care.

Adult↗
PubMed2006

The cost of Latin American science Introduction for the second issue of CBP-Latin America.

Latin American researchers in science and engineering (S&E), including those in biology and biomedical sciences, are frequently exposed to unstable conditions of financial support, material and human resources, and a limited number of positions at public and private institutions. Such uncertainties impose continuous challenges for the scientific community which, in the best of cases, responds with careful planning and creativity, and in the worst scenario endures the migration of scientists to the USA or Europe. Still, the number of scientific publications from Latin American institutions in the last decade increased at a much faster rate than publications from the USA and Canada. A brief analysis per country of the gross domestic product (GDP) spent in research and development (R&D) and the S&E production reported by the Pascal bibliographic database suggests that the number and quality of S&E publications is directly proportional to the financial support for R&D. However, the investment in R&D in Latin America did not increase at the same rate (from 0.49 to 0.55% of GDP, from 1990 to 2003) at which S&E publications did in the same period (2.9-fold increase, from 1988 to 2001). In Latin America, the traditional financial support for scientific research continues to be from federal and state government funds, associated in some cases with institutional funds that are mostly directed towards administrative costs and infrastructure maintenance. The aim of this introduction is to briefly discuss the production cost of articles published in refereed S&E journals, including the cost of the scientific research behind them, and, at the same time, to increase the awareness of the high quality of scientific research in Latin American institutions despite the many challenges, especially financial constraints, faced by their scientists. The second issue of Comparative Biochemistry and Physiology dedicated to Latin America ("The Face of Latin American Comparative Biochemistry and Physiology") celebrates, by means of 26 manuscripts from five countries, the diversity and quality of biological science in the continent.

Biological Science Disciplines↗
PubMed2004

Follow-up by mail in clinical trials: does questionnaire length matter?

In large clinical trials where outcome assessment is possible using questionnaires, it may be more cost-effective to mail them to patients than to conduct interviews in-person. However, nonresponse to mailed questionnaires reduces the effective sample size and can introduce bias. We conducted a systematic review and meta-analysis of randomized controlled trials evaluating the effect of questionnaire length on response rates. We searched 14 electronic bibliographic databases, the reference lists of relevant trials, and we contacted the authors of eligible trials to ask about unpublished data. For each trial identified, we used logistic regression to estimate the odds ratio for response per one page increase in the number of pages included in the questionnaire. We pooled the regression coefficients in a random effects meta-analysis. Heterogeneity among the coefficients was assessed using a chi-square test at a 5% significance level. We specified a priori that the reduction in the odds of response per one page increase would be greatest among trials comparing relatively short questionnaires. We used meta regression to examine the relationships between the regression coefficients, the length of the questionnaires used in each trial, and other study characteristics. A total of 38 randomized controlled trials were identified where participants were allocated to questionnaires of differing lengths and where the number of pages used was known. There was significant heterogeneity between the regression coefficients estimated from each trial. In meta regression, most of the heterogeneity was explained by variation in the length of the questionnaires used in each trial. Among trials in which the shortest questionnaire was a postcard, the odds of response were more than halved for each additional page used (0.39; 95% CI 0.34 to 0.45). In the remaining trials, pooled effect sizes were much smaller. In trials of one page compared with either two or three pages, the odds of response per one page increase was 1.01 (95% CI 0.82 to 1.24). For one page compared with four or more pages, and for two or more pages compared with longer alternatives, the odds ratios per one page increase were 0.90 (95% CI 0.83 to 0.98) and 0.98 (95% CI 0.96 to 0.99), respectively. There were no statistically significant associations between trial results and other study characteristics. It appears that response can be increased by using a shorter questionnaire. Moderate changes to the length of shorter questionnaires will be more effective than moderate changes to the length of longer questionnaires. If a choice of follow-up questionnaire exists for a clinical trial, the shorter one should be used. If a new follow-up questionnaire is to be designed, it should be made as short as possible without compromising the data collection requirements of the trial.

Follow-Up Studies↗