Effectiveness of rotavirus vaccine against hospitalized rotavirus diarrhea: A case–control study

Rotavirus is one of the leading cause of hospitalization and outpatients visits among children under five years. This study evaluated overall and genotype-specific vaccine effectiveness of oral monovalent rotavirus vaccine (G1P[8] strain) in preventing hospital admission of Brazilian children with rotavirus acute diarrhea.     

Does long-term lactation protect premenopausal women against hypertension risk? A Korean women's cohort study

BACKGROUND: Little is known about the long-term effect of lactation on maternal cardiovascular health except for a few animal or human experimental studies. The objective of this study was to examine the effects of lactation on the incidence of hypertension in premenopausal women. METHODS: The data were derived from a cohort study with 6 years follow-up (1995-2000). The cohort was composed of 177,749 Korean premenopausal women, aged 20-59, who had medical evaluations in 1992 and 1994. During the follow-up, blood pressure was measured as part of the 1996, 1998, and 2000 periodic examinations. RESULTS: In multivariate Cox proportional hazard models, lactation decreased the risk of hypertension (risk ratio, 0.92; 95% confidence interval, 0.90-0.96). Compared with women who with no history of lactation, 1-6 months of lactation decreased the risk of hypertension (RR, 0.90; 95% CI, 0.87-0.93), as did 7-12 months (RR, 0.92; 95% CI, 0.87-0.98) or 13-18 months (RR, 0.93; 95% CI, 0.86-0.99). In particular, the coexistence of obesity and no lactation increased the risk of hypertension (P for interaction = 0.028). CONCLUSION: This finding suggests that lactation may be a protective factor against hypertension among premenopausal women.     

Assessing different measures of population-level vaccine protection using a case–control study

BackgroundCase–control studies have not been examined for their utility in assessing population-level vaccine protection in individually randomized trials.MethodsWe used the data of a randomized, placebo-controlled trial of a cholera vaccine to compare the results of case–control analyses with those of cohort analyses. Cases of cholera were selected from the trial population followed for three years following dosing. For each case, we selected 4 age-matched controls who had not developed cholera. For each case and control, GIS was used to calculate vaccine coverage of individuals in a surrounding “virtual” cluster. Specific selection strategies were used to evaluate the vaccine protective effects.Results66,900 out of 108,389 individuals received two doses of the assigned regimen. For direct protection among subjects in low vaccine coverage clusters, we observed 78% (95% CI: 47–91%) protection in a cohort analysis and 84% (95% CI: 60–94%) in case–control analysis after adjusting for confounding factors. Using our GIS-based approach, estimated indirect protection was 52% (95% CI: 10–74%) in cohort and 76% (95% CI: 47–89%) in case control analysis. Estimates of total and overall effectiveness were similar for cohort and case–control analyses.ConclusionThe findings show that case–control analyses of individually randomized vaccine trials may be used to evaluate direct as well as population-level vaccine protection.     

Vitamin A liver store: a case–control study

The present study aims to assess the vitamin A liver store in individuals who died of several causes and to compare them with those who died of violent causes. A case–control study was performed with 60 individuals, where 30 died of violent causes (control) and 30 of other causes (cardiovascular diseases, infections, other chronic degenerative diseases, several causes). According to the cause of death, the mean retinol from liver stores was 281.5±63.50 mg/g for individuals who died of violent causes—a significantly higher amount (P<0.05) than those observed in the other group (105.4±87.54 mg/g by cardiovascular diseases, 88.1±78.03 mg/g by infections, 162.4±119.19 mg/g by other chronic degenerative diseases and 205.5±126.63 mg/g by several causes). The highest prevalence of low vitamin A was observed in individuals who died of infections and cardiovascular diseases, which emphasizes the role of vitamin A in these pathological processes.     

Patterns of bias due to differential misclassification by case–control status in a case–control study

BACKGROUND: Case-control study is still one of the most commonly used study designs in epidemiological research. Misclassification of case-control status remains a significant issue because it will bias the results of a case-control study. There exist two types of misclassification, differential versus nondifferential. It is commonly accepted that nondifferential misclassification will bias the results of the study towards the null hypothesis. Conversely, no reports have assessed the impact and direction of differential misclassification on odds ratio (OR) estimate. The goal of the present study is to demonstrate by statistical derivation that patterns exist on the bias induced by differential misclassification. METHODS: Based on a 2 x 2 case-control study design, we derive the odds ratio without misclassification, and those with misclassification according to: (1) controls are misclassified as cases by exposure status; (2) cases are misclassified as controls by exposure status; and (3) both controls and cases are misclassified by exposure status simultaneously. Furthermore, mathematical derivations are shown for each of the ratios of the two odds ratios with and without misclassification. These methods are carried out by simulation analyses. RESULTS: Simulation analyses show that quite a number of biased odds ratios tend to move away from the null hypothesis and result in approaching zero or infinity with increasing proportion of misclassification among cases, controls, or both. These patterns are associated with the exposure status and the values of unbiased odds ratio (<1, 1, or >1). CONCLUSIONS: Our findings suggest that, unlike nondifferential misclassification, differential misclassification of case-control status in a case-control study may not weaken the exposure-outcome association towarding the null hypothesis. Care needs to be taken for interpreting the results of a case-control study when there exists differential misclassification bias, a practical issue in epidemiological research.     

A nested case–control study of low birthweight among cosmetologists

Objective  

This study was designed to determine whether licensed female cosmetologists with a low birthweight child were more likely to perform specific occupational tasks during pregnancy than cosmetologists who had a normal weight child. We also investigated certain salon characteristics in relation to low birthweight status.     

A case–control study of occupational exposures and systemic sclerosis

Objectives A case–control study was conducted in Verona, Italy, to assess the relationship between occupation, occupational exposures and systemic sclerosis (SSc).Methods Fifty-five cases (46 female and nine male) and 171 controls were recruited. Interviews provided work histories, including job titles, industry and likelihood of occupational exposure to silica, hand–arm vibration, organic solvents, and other chemicals. Odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated.Results Female teachers (OR 3.4, 95% CI 1.2–10.1) and textile workers (OR 2.1, 95% CI 1.0–4.6) were at an increased risk of SSc. Compared with those never exposed, age-adjusted and gender-adjusted ORs were 2.3 (95% CI 1.0–5.4) among subjects exposed to organic solvents, 2.5 (95% CI 0.8–8.0) for exposure to selected chemicals, 1.7 (95% CI 0.4–7.6) for exposure to silica, and 1.5 (95% CI 0.5–4.8) for usage of vibrating tools. When data analysis was stratified according to gender, only men showed a significant increase in risk for exposure to solvents and selected chemicals.Conclusions The findings of this study tend to support the role of organic solvents and certain chemicals in SSc causation. The association with teaching and working in the textile industry suggests that other exposures are involved in the aetiology of SSc among women. However, because of the small number of subjects, particularly in stratified analyses, chance cannot be ruled out as an explanation of some findings of this study.     

Moderate physical activity and prostate cancer risk: A case–control study in china

A case-control study was conducted to investigate the association between physical activity and prostate cancer risk in China. A total of 130 recent histopathologically confirmed cancer cases and 274 controls were interviewed. Information collected included type, intensity and duration of various physical activities. The adjusted odds ratios of prostate cancer risk for physical activity variables were obtained from multivariate logistic regression models. Results showed that moderate physical activity was inversely related to the prostate cancer risk, with adjusted odds ratio being 0.20 (95% confidence interval 0.07–0.62) for the upper vs. the lower quartiles of weekly metabolic equivalent task-hours. The dose-response relationship was also significant (p = 0.015). The findings suggest that moderate physical activity may be protective against prostate cancer for Chinese men.This revised was published online in April 2005. In the previous version the article category was missing.     

Risk factors for measles infection in 0–7 month old children in China after the 2010 nationwide measles campaign: A multi-site case–control study, 2012–2013

IntroductionEndemic measles persists in China, despite >95% reported coverage of two measles-containing vaccine doses and nationwide campaign that vaccinated more than 100 million children in 2010. We performed a case–control study in six Chinese provinces during January 2012 through June 2013 to identify risk factors for measles infection among children aged 0–7 months.MethodsChildren with laboratory-confirmed measles were neighborhood matched with three controls. We interviewed parents of case and control infants on potential risk factors for measles. Adjusted matched odds ratios (mOR) and 95% confidence intervals (CIs) were calculated by multivariable conditional logistic modeling. We calculated attributable fractions for risk factors that could be interpreted as causal.ResultsEight hundred thirty cases and 2303 controls were enrolled. In multivariable analysis, male sex (mOR 1.6 [1.3, 2.0]), age 5–7 months (mOR 3.9 [3.0, 5.1]), migration between counties (mOR 2.3 [1.6, 3.4]), outpatient hospital visits (mOR 9.4 [6.6, 13.3]) and inpatient hospitalization (mOR 107.1 [48.8, 235.1]) were significant risk factors. The calculated attributable fractions for hospital visits was 43.1% (95% CI: 40.1, 47.5%) adjusted for age, sex and migration.ConclusionsHospital visitation was the largest risk factor for measles infection in infants. Improved hospital infection control practices would accelerate measles elimination in China.     

Clinical effectiveness of 23-valent pneumococcal polysaccharide vaccine against pneumonia in middle-aged and older adults: A matched case–control study

The 23-valent polysaccharide pneumococcal vaccine is currently recommended in elderly and high-risk adults. Its efficacy against invasive pneumococcal disease has been demonstrated, but its effectiveness in preventing pneumonia remains uncertain. This study assessed the clinical effectiveness of vaccination against pneumonia among middle-aged and older adults. We conducted a population-based case–control study including 304 case patients over 50 years old with radiographically confirmed pneumococcal pneumonia (94 bacteremic and 210 nonbacteremic cases) and 608 outpatient control subjects (matched by primary care centre, age, sex and risk stratum). Adjusted odds ratios (ORs) for vaccination were calculated using conditional logistic regression, controlling for underlying conditions. Vaccine effectiveness against all pneumococcal pneumonia was 48% (OR: 0.52; 95% confidence interval [CI]: 0.37–0.73). Vaccination was effective against bacteremic cases (OR: 0.34; 95% CI: 0.27–0.66) as well as nonbacteremic cases (OR: 0.58; 95% CI: 0.39–0.86). Vaccine effectiveness was highest against bacteremic infections caused by vaccine types (OR: 0.24; 95% CI: 0.09–0.66). These findings confirm the effectiveness of the vaccine against invasive disease, but they also support the benefit of vaccination in preventing nonbacteremic pneumococcal pneumonia.     

Relation between overweight, diabetes, stress and hypertension: A case–control study in Yarumal – Antioquia, Colombia

Aims: The aim of this study was to assess the association between overweight, diabetes, stress and other postulated risk factors for a high blood pressure, on the risk of hypertension. Methods and Results: This matched case–control study included 228 cases randomly selected in a rural adult population in Yarumal – Antioquia, Colombia. For every case, one control, individually matched by age (± 5 years), sex and residence, was selected from the general population. Conditional logistic regression was used to estimate odds ratios (OR). Obese people (body mass index (BMI) 30 kg/m²) showed an increased OR of hypertension compared to those with a BMI < 25 kg/m², OR: 3.83 [95% confidence interval (CI): 1.83–8.00]. A high level of psychological stress was associated with hypertension (measured on a tension–anxiety scale), OR: 5.02 (95% CI: 2.25–11.19). A positive association was also observed for diabetes although it was of borderline significance, OR: 2.58 (95% CI: 0.88–7.55). Having a family member with hypertension or myocardial infarction was related to a higher risk of hypertension (p < 0.05). Conclusions: This study provides evidence that BMI, stress (feelings of anxiety or tension), and diabetes are independently associated with an increased risk of hypertension in a rural area of Colombia.     

Does gender really matter in contaminant exposure? A case study using invertebrate models

Exposure to contaminants in the environment is indiscriminate and multiple species/populations of all sexes are potentially at risk. In this paper we examine the current information available on gender specific differences in invertebrates following exposure to environmental contaminants. Because of their close association with the environment and diversity of habitats, invertebrates are uniquely at risk for adverse responses to pollutants. Since 97% of all animal species are invertebrates, it would be impossible to cover each of the phyla in this review. Instead, this paper discusses major invertebrate species including insects (Periplaneta americana, Panorpa vulgaris, Lycosa hilaris, Haematobia irritans irritans (L.), and Drosophilia melanogaster), nematodes (Caenorhabditis elegans), crustaceans (Streptocephalus dichotomus, Amphiascus tenuiremis, Microarthridion littorale, Tisbe bulbisetosa, Acartia tonsa, and Palaemonetes pugio), mollusks (Pinctada fucata martensii, Ilyanassa obsoleta, Nucella lapillus, Hinia reticulata, Thais clavigera, and Mercenaria mercenaria), corals (Euphyllia ancora and Montipara capitata), and echinoderms (Asterias rubens) that have been used in studies examining the differences between males and females. Our discussion focuses on gender differences that occur in both toxicokinetic mechanisms (uptake and elimination, metabolism and physiology) and other toxicological endpoints (survival and behavior as well as morphology and development). It will become evident that the endocrine systems of invertebrates have many traits and/or pathways that are comparable to those observed in higher organisms. Yet the sensitivity of some elements of the invertebrate endocrine system, e.g., disruption of neuropeptide hormone signaling following TBT exposure, highlights the uniqueness of their systems and their potential for disruption.     

Dietary cadmium intake and breast cancer risk in Japanese women: A case–control study

Cadmium, an environmental pollutant, may act like an estrogen and be a potential risk factor for estrogen-dependent diseases such as breast cancer. We examined the hypothesis that higher dietary cadmium intake is associated with risk of overall and hormone receptor-defined breast cancer in Japanese women, a population with a relatively high cadmium intake. The study was conducted under a case–control design in 405 eligible matched pairs from May 2001 to September 2005 at four hospitals in Nagano Prefecture, Japan. Dietary cadmium intake was estimated using a food frequency questionnaire. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of breast cancer and its hormone-receptor-defined subtypes were calculated by tertile of dietary cadmium intake. We found no significant association between dietary cadmium and risk of total breast cancer in either crude or multivariable-adjusted analysis. Adjusted ORs for tertiles of cadmium intake were 1.00, 1.19, and 1.23 (95% CI, 0.76–2.00; P for trend = 0.39) for whole breast cancer. Further, no significant associations were seen across strata of menopausal status, smoking, and diabetes in multivariable-adjusted models except for adjusted OR for continuous cadmium intake in postmenopausal women. A statistically significant association was found for estrogen receptor-positive (ER+) tumors among postmenopausal women (adjusted OR = 1.00, 1.16, and 1.94 [95% CI, 1.04–3.63; P for trend = 0.032]). Although the present study found no overall association between dietary cadmium intake and breast cancer risk, higher cadmium intake was associated with increased risk of ER+ breast cancer in postmenopausal women, at least at regular intake levels in Japanese women in the general population. Further studies are needed to confirm this association.     

Single nucleotide polymorphisms in candidate genes and dengue severity in children: A case–control,functional and meta-analysis study

Dengue is an arthropod-borne emerging viral disease with high morbidity and mortality risk in tropical countries like Brazil. Clinical manifestations are vast, ranging from asymptomatic to most severe forms of dengue such as shock. Previous data have shown that host genetics play a role in disease susceptibility and severity. Herein, we have tested the association of single nucleotide polymorphisms (SNPs) at TNF, IL10, MIF, DCSIGN, CLEC5A, NOD2, CCR5 and MRC1 as candidate genes using a matched case–control study design including 88 severe children cases of dengue patients and 335 healthy unrelated subjects that was also separated in IgG⁺ and IgG⁻ controls. We demonstrated that the TT genotype of CLEC5A SNP (rs1285933 C>T) is associated with dengue severity (OR = 2.25; p = 0.03) and that GG genotype of −336G>A DCSIGN (CD209) SNP is associated with protection to severe dengue (OR = 0.12; p = 0.04). Both comparisons were borderline significant when cases were compared with IgG⁺ controls subgroup. Nevertheless, genotype–phenotype correlation was also assessed using serum levels of TNF from infected patients at the onset of dengue fever, and CT/TT carriers in CLEC5A secreted higher levels of TNF than CC individuals in 5–7 days of infection. No significant difference was observed in TNF levels between genotypes GG versus AG/AA at DCSIGN promoter. Next, we performed a meta-analysis retrieving results from the literature for −336G>A DCSIGN and −308G>A TNF SNPs demonstrating that the consensus estimates of these SNPs indicated no association with dengue severity (when compared to Dengue fever) in the overall analysis. But, a subgroup analysis in the −336G>A DCSIGN, the G allele was associated with severe dengue susceptibility in Asians (OR_allele = 2.77; p = 0.0001; OR_carriers = 2.99; p = 0.0001) and protection in Brazilians (OR_allele=0.66; p=0.013). In summary, our results suggest that genetic variations at CLEC5A increase the risk and regulate TNF secretion in dengue severity among Brazilians. Also, combined data of the literature suggest population-specific effect of the −336 DCSIGN SNP more prominent in Asians and in a different direction than Brazilians.     

Do ethnic groups use health services like the majority of the population? A study from Quebec, Canada

The purpose of this study was to compare the use of medical services over a period of one year by members of ethnic groups and native Quebecers in Canada, while controlling for a number of confounding factors. The objective was to determine whether the two groups made the same number of medical visits to the same sites (private offices, outpatient clinic and emergency room and hospital inpatient care) and the same types of physicians (general practitioners, specialists). Two sources of data were used. The first was the Quebec Health Survey conducted in 1987 on a representative sample of 31,995 noninstitutionalized persons. Through personal interviews and self-administered questionnaires, data were collected on the demographic characteristics and health status of the respondents. The second source of data was the Quebec physician claims database, which contains a complete registry of services paid to physicians on a fee for service basis in the 12 months prior to the survey. The two databases were linked at the individual level (success rate is 88%). Members of ethnic groups aged 15 years and older were then individually matched to native Quebecers having the same six characteristics (age, gender, household income, access to health care facilities, perceived health and overall health). Final sample size was 1182 (divided equally into the two study groups). Results showed that neither the average number of medical services used over a year by the two groups nor the number of users differed. However, ethnic groups made more visits to specialists in private offices. Although not definite, possible explanations of these results are discussed. It is concluded that health care professionals should be sensitive to the particular needs of ethnic groups in order to provide them with accessible and appropriate services.     

A population-based case–control teratologic study of oral chloramphenicol treatment during pregnancy

The objective of the study was to check the human teratogenic potential of oral chloramphenicol treatments during pregnancy. Pair analysis of cases with congenital abnormalities and matched population controls was performed in the large population-based dataset of the Hungarian Case–Control Surveillance of Congenital Abnormalities, 1980–1996. Of 38,151 pregnant women who had babies without any defects (control group), 51 (0.13%), while of 22,865 pregnant women who had newborn infants or fetuses with congenital abnormalities, 52 (0.23%) pregnant women were treated with oral chloramphenicol. The case–control pair analysis did not show any human teratogenic potential of chloramphenicol during the second–third months of pregnancy in the different groups of congenital abnormalities. The occurrence of chloramphenicol treatment in the total control group as referent was compared with the occurrence of chloramphenicol treatment in the different congenital abnormality groups during the second–third months of gestation (i.e., in the critical period for major congenital abnormalities) and a higher adjusted OR for this drug was found only in the group with undescended testis based on only two cases. At the evaluation of medically documented chloramphenicol treatment a higher OR was not found in any congenital abnormalities. Thus, chloramphenicol treatment during early pregnancy presents little, if any, teratogenic risk to the fetus in humans.     

A nested case-control study measuring pertussis vaccine effectiveness and duration of protection in Manitoba,Canada, 1992–2015: A Canadian Immunization Research Network Study

BackgroundPertussis persists in Manitoba despite the universal availability of pertussis vaccines. Recent cases have included previously vaccinated individuals, raising concerns about declining vaccine effectiveness (VE). We measured pertussis VE and duration of protection using Manitoba’s provincial immunization and communicable disease registries.MethodsUsing a nested case-control design, individuals with laboratory-confirmed pertussis in Manitoba diagnosed between April 1, 1992, and March 31, 2015, were matched to up to five population-based controls on age, gender, geography, and case physician or number of physician visits. Conditional logistic regression was used to estimate VE against pertussis for both the whole-cell (wP) and acellular (aP) pertussis vaccines. Duration of protection was assessed using time since last dose.ResultsData on 534 eligible cases and 2614 controls were available for analysis. The adjusted VE estimate for aP-containing vaccines was 85% (95%CI: 74–91%); VE was 89% (66–96%) one to three years after the last vaccination. The adjusted VE of wP-containing vaccines was –15% (–91–31%) during a large outbreak in 1994 and 1995 compared to 35% (–26–66%) during non-outbreak years.ConclusionsOur estimates suggest that the aP vaccine was effective in preventing pertussis since its introduction in Manitoba. VE was lower during a large outbreak, highlighting the importance of separately analyzing outbreak periods when estimating pertussis VE over time.