Effect of reminders on mitigating participation bias in a case-control study

BACKGROUND: Researchers commonly employ strategies to increase participation in health studies. These include use of incentives and intensive reminders. There is, however, little evidence regarding the quantitative effect that such strategies have on study results. We present an analysis of data from a case-control study of Campylobacter enteritis in England to assess the usefulness of a two-reminder strategy for control recruitment. METHODS: We compared sociodemographic characteristics of participants and non-participants, and calculated odds ratio estimates for a wide range of risk factors by mailing wave. RESULTS: Non-participants were more often male, younger and from more deprived areas. Among participants, early responders were more likely to be female, older and live in less deprived areas, but despite these differences, we found little evidence of a systematic bias in the results when using data from early reponders only. CONCLUSIONS: We conclude that the main benefit of using reminders in our study was the gain in statistical power from a larger sample size

Knowledge of stroke risk factors among primary care patients with previous stroke or TIA: a questionnaire study

<p>Abstract</p> <p>Background</p> <p>Survivers of stroke or transient ischaemic attacks (TIA) are at risk of new vascular events. Our objective was to study primary health care patients with stroke/TIA regarding their knowledge about risk factors for having a new event of stroke/TIA, possible associations between patient characteristics and patients' knowledge about risk factors, and patients' knowledge about their preventive treatment for stroke/TIA.</p> <p>Methods</p> <p>A questionnaire was distributed to 240 patients with stroke/TIA diagnoses, and 182 patients (76%) responded. We asked 13 questions about diseases/conditions and lifestyle factors known to be risk factors and four questions regarding other diseases/conditions ("distractors"). The patients were also asked whether they considered each disease/condition to be one of their own. Additional questions concerned the patients' social and functional status and their drug use. The t-test was used for continuous variables, chi-square test for categorical variables, and a regression model with variables influencing patient knowledge was created.</p> <p>Results</p> <p>Hypertension, hyperlipidemia and smoking were identified as risk factors by nearly 90% of patients, and atrial fibrillation and diabetes by less than 50%. Few patients considered the distractors as stroke/TIA risk factors (3-6%). Patients with a family history of cardiovascular disease, and patients diagnosed with carotid stenosis, atrial fibrillation or diabetes, knew these were stroke/TIA risk factors to a greater extent than patients without these conditions. Atrial fibrillation or a family history of cardiovascular disease was associated with better knowledge about risk factors, and higher age, cerebral haemorrhage and living alone with poorer knowledge. Only 56% of those taking anticoagulant drugs considered this as intended for prevention, while 48% of those taking platelet aggregation inhibitors thought this was for prevention.</p> <p>Conclusions</p> <p>Knowledge about hypertension, hyperlipidemia and smoking as risk factors was good, and patients who suffered from atrial fibrillation or carotid stenosis seemed to be well informed about these conditions as risk factors. However, the knowledge level was low regarding diabetes as a risk factor and regarding the use of anticoagulants and platelet aggregation inhibitors for stroke/TIA prevention. Better teaching strategies for stroke/TIA patients should be developed, with special attention focused on diabetic patients.</p

Variations in cardiovascular disease under-diagnosis in England: national cross-sectional spatial analysis

BACKGROUND: There is under-diagnosis of cardiovascular disease (CVD) in the English population, despite financial incentives to encourage general practices to register new cases. We compared the modelled (expected) and diagnosed (observed) prevalence of three cardiovascular conditions- coronary heart disease (CHD), hypertension and stroke- at local level, their geographical variation, and population and healthcare predictors which might influence diagnosis. METHODS: Cross-sectional observational study in all English local authorities (351) and general practices (8,372) comparing model-based expected prevalence with diagnosed prevalence on practice disease registers. Spatial analyses were used to identify geographic clusters and variation in regression relationships. RESULTS: A total of 9,682,176 patients were on practice CHD, stroke and transient ischaemic attack, and hypertension registers. There was wide spatial variation in observed: expected prevalence ratios for all three diseases, with less than five per cent of expected cases diagnosed in some areas. London and the surrounding area showed statistically significant discrepancies in observed: expected prevalence ratios, with observed prevalence much lower than the epidemiological models predicted. The addition of general practitioner supply as a variable yielded stronger regression results for all three conditions. CONCLUSIONS: Despite almost universal access to free primary healthcare, there may be significant and highly variable under-diagnosis of CVD across England, which can be partially explained by persistent inequity in GP supply. Disease management studies should consider the possible impact of under-diagnosis on population health outcomes. Compared to classical regression modelling, spatial analytic techniques can provide additional information on risk factors for under-diagnosis, and can suggest where healthcare resources may be most needed

Impact of socio-economic factors on stroke prevalence among urban and rural residents in Mainland China

<p>Abstract</p> <p>Background</p> <p>An inverse relationship between better socioeconomic status (total household income, education or occupation) and stroke has been established in developed communities, but family size has generally not been considered in the use of socioeconomic status indices. We explored the utility of Family Average Income (FAI) as a single index of socioeconomic status to examine the association with stroke prevalence in a region of China, and we also compared its performance as a single index of socioeconomic status with that of education and occupation.</p> <p>Methods</p> <p>A population-based cross-sectional study was conducted in Nanjing municipality of China during the period between October 2000 and March 2001. A total of 45 administrative villages were randomly selected using a multi-stage sampling approach and all regular local residents aged 35 years or above were included. Descriptive statistics and logistic regression models were used in analysis.</p> <p>Results</p> <p>The overall prevalence of diagnosed stroke was 1.54% in all 29,340 eligible participants. An elevated prevalence of stroke was associated with increasing levels of FAI. After adjustment for basic demographic variables (age, urban/rural area and gender) and a group of defined conventional risk factors, this gradient still remained significant, with participants in the highest (OR = 1.94, 95% CI = 1.40, 2.70) and middle (OR = 1.43, 95% CI = 1.01, 2.02) categories of FAI having higher risks compared with the lowest category. A significantly elevated OR of stroke prevalence was found in white collar workers compared to blue collar workers, while no significant relationship was observed with education.</p> <p>Conclusion</p> <p>Our study consistently revealed that the prevalence of stroke was associated with increasing levels of all SES indices, including FAI, education, and occupation. However, a significant gradient was only observed with FAI after controlling for important confounding factors. The findings suggested that, compared with occupation and education, FAI could be used as a more sensitive index of socio-economic status for public health studies in China.</p

Heavy burden of non-communicable diseases at early age and gender disparities in an adult population of Burkina Faso: world health survey

<p>Abstract</p> <p>Background</p> <p>WHO estimates suggest that age-specific death rates from non-communicable diseases are higher in sub-Saharan Africa than in high-income countries. The objectives of this study were to examine, in Burkina Faso, the prevalence of non-communicable disease symptoms by age, gender, socioeconomic group and setting (rural/urban), and to assess gender and socioeconomic inequalities in the prevalence of these symptoms.</p> <p>Methods</p> <p>We obtained data from the Burkina Faso World Health Survey, which was conducted in an adult population (18 years and over) with a high response rate (4822/4880 selected individuals). The survey used a multi-stage stratified random cluster sampling strategy to identify participants. The survey collected information on socio-demographic and economic characteristics, as well as data on symptoms of a variety of health conditions. Our study focused on joint disease, back pain, angina pectoris, and asthma. We estimated prevalence correcting for the sampling design. We used multiple Poisson regression to estimate associations between non-communicable disease symptoms, gender, socioeconomic status and setting.</p> <p>Results</p> <p>The overall crude prevalence and 95% confidence intervals (CI) were: 16.2% [13.5; 19.2] for joint disease, 24% [21.5; 26.6] for back pain, 17.9% [15.8; 20.2] for angina pectoris, and 11.6% [9.5; 14.2] for asthma. Consistent relationships between age and the prevalence of non-communicable disease symptoms were observed in both men and women from rural and urban settings. There was markedly high prevalence in all conditions studied, starting with young adults. Women presented higher prevalence rates of symptoms than men for all conditions: prevalence ratios and 95% CIs were 1.20 [1.01; 1.43] for joint disease, 1.42 [1.21; 1.66] for back pain, 1.68 [1.39; 2.04] for angina pectoris, and 1.28 [0.99; 1.65] for asthma. Housewives and unemployed women had the highest prevalence rates of non-communicable disease symptoms.</p> <p>Conclusions</p> <p>Our work suggests that social inequality extends into the distribution of non-communicable diseases among social groups and supports the thesis of a differential vulnerability in Burkinabè women. It raises the possibility of an abnormally high rate of premature morbidity that could manifest as a form of premature aging in the adult population. Increased prevention, screening and treatment are needed in Burkina Faso to address high prevalence and gender inequalities in non-communicable diseases.</p

A likelihood ratio approach for utilizing case-control data in the clinical classification of rare sequence variants:Application to BRCA1 and BRCA2

A large number of variants identified through clinical genetic testing in disease susceptibility genes are of uncertain significance (VUS). Following the recommendations of the American College of Medical Genetics and Genomics (ACMG) and Association for Molecular Pathology (AMP), the frequency in case-control datasets (PS4 criterion) can inform their interpretation. We present a novel case-control likelihood ratio-based method that incorporates gene-specific age-related penetrance. We demonstrate the utility of this method in the analysis of simulated and real datasets. In the analysis of simulated data, the likelihood ratio method was more powerful compared to other methods. Likelihood ratios were calculated for a case-control dataset of BRCA1 and BRCA2 variants from the Breast Cancer Association Consortium (BCAC) and compared with logistic regression results. A larger number of variants reached evidence in favor of pathogenicity, and a substantial number of variants had evidence against pathogenicity findings that would not have been reached using other case-control analysis methods. Our novel method provides greater power to classify rare variants compared with classical case-control methods. As an initiative from the ENIGMA Analytical Working Group, we provide user-friendly scripts and preformatted Excel calculators for implementation of the method for rare variants in BRCA1, BRCA2, and other high-risk genes with known penetrance.</p

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency–Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research

Guidelines for management of ischaemic stroke and transient ischaemic attack 2008

This article represents the update of the European Stroke Initiative Recommendations for Stroke Management. These guidelines cover both ischaemic stroke and transient ischaemic attacks, which are now considered to be a single entity. The article covers referral and emergency management, Stroke Unit service, diagnostics, primary and secondary prevention, general stroke treatment, specific treatment including acute management, management of complications, and rehabilitation

Cost effectiveness of COX 2 selective inhibitors and traditional NSAIDs alone or in combination with a proton pump inhibitor for people with osteoarthritis.

OBJECTIVES: To investigate the cost effectiveness of cyclo-oxygenase-2 (COX 2) selective inhibitors and traditional non-steroidal anti-inflammatory drugs (NSAIDs), and the addition of proton pump inhibitors to these treatments, for people with osteoarthritis. DESIGN: An economic evaluation using a Markov model and data from a systematic review was conducted. Estimates of cardiovascular and gastrointestinal adverse events were based on data from three large randomised controlled trials, and observational data were used for sensitivity analyses. Efficacy benefits from treatment were estimated from a meta-analysis of trials reporting total Western Ontario and McMaster Universities (WOMAC) osteoarthritis index score. Other model inputs were obtained from the relevant literature. The model was run for a hypothetical population of people with osteoarthritis. Subgroup analyses were conducted for people at high risk of gastrointestinal or cardiovascular adverse events. Comparators Licensed COX 2 selective inhibitors (celecoxib and etoricoxib) and traditional NSAIDs (diclofenac, ibuprofen, and naproxen) for which suitable data were available were compared. Paracetamol was also included, as was the possibility of adding a proton pump inhibitor (omeprazole) to each treatment. MAIN OUTCOME MEASURES: The main outcome measure was cost effectiveness, which was based on quality adjusted life years gained. Quality adjusted life year scores were calculated from pooled estimates of efficacy and major adverse events (that is, dyspepsia; symptomatic ulcer; complicated gastrointestinal perforation, ulcer, or bleed; myocardial infarction; stroke; and heart failure). RESULTS: Addition of a proton pump inhibitor to both COX 2 selective inhibitors and traditional NSAIDs was highly cost effective for all patient groups considered (incremental cost effectiveness ratio less than pound1000 (euro1175, $1650)). This finding was robust across a wide range of effectiveness estimates if the cheapest proton pump inhibitor was used. In our base case analysis, adding a proton pump inhibitor to a COX 2 selective inhibitor (used at the lowest licensed dose) was a cost effective option, even for patients at low risk of gastrointestinal adverse events (incremental cost effectiveness ratio approximately pound10 000). Uncertainties around relative adverse event rates meant relative cost effectiveness for individual COX 2 selective inhibitors and traditional NSAIDs was difficult to determine. CONCLUSIONS: Prescribing a proton pump inhibitor for people with osteoarthritis who are taking a traditional NSAID or COX 2 selective inhibitor is cost effective. The cost effectiveness analysis was sensitive to adverse event data and the specific choice of COX 2 selective inhibitor or NSAID agent should, therefore, take into account individual cardiovascular and gastrointestinal risks