Effectiveness of mass neonatal BCG vaccination in the prevention of pulmonary tuberculosis: a case-control study in Nagpur, India

SETTING: Government Medical College, Nagpur, India, a tertiary care hospital. OBJECTIVE: To estimate the effectiveness of mass neonatal BCG vaccination in the prevention of pulmonary tuberculosis in Nagpur, India. DESIGN: A hospital-based pair-matched case-control study with a case of 1:3, including 144 cases of pulmonary tuberculosis and 432 controls. RESULTS: The overall vaccine effectiveness estimated in the present study was 60% (95% Confidence Interval [CI] 43%-72%). The protective effect was more in males in the age group 21-30 years. The prevented fraction was 39% (95% CI 24%-52%). CONCLUSION: The moderate effectiveness demonstrated in this study needs to be substantiated for other forms of tuberculosis by undertaking community-based case-control studies, before attempting to justify the use of mass neonatal BCG vaccination strategy as a part of the national programme.     

Elevated plasma lipid peroxides at the onset of nonaffective psychosis

OBJECTIVE: To identify risk factors for Klebsiella pneumoniae bloodstream infections (BSI) in neonates in a hospital in the Kingdom of Saudi Arabia (KSA). DESIGN: Two case-control studies among hospitalized neonates during February 15-May 14, 1991, and a procedural and microbiological investigation. SETTING: Hospital A, a maternity and children's hospital in KSA. PATIENTS: Case patients had a blood culture positive for K pneumoniae after >2 days of hospitalization and had no evidence of a nonblood primary site of infection. RESULTS: When the 20 case patients were compared with controls, hospitalization in a critical-care unit (odds ratio [OR], 5.5; 95% confidence interval [CI95], 1.20-51.1; P=.03) was identified as a risk factor. When the case patients were compared with a second set of controls matched by critical-care status, receipt of a particular intravenous fluid (D10%/0.2NS; OR, 11.0; CI95, 1.42-85.2; P=.009) or a blood product (OR undefined; P=.04) were identified as risk factors. Infusates were administered via umbilical catheters for most case and control patients (19/20 vs 15/20, P>.05); catheters were manipulated more frequently in patients in critical-care units. Umbilical catheter tip, skin, or mucus membrane K pneumoniae colonization occurred in 47% and 53% of evaluated case and control patients, respectively. Available K pneumoniae isolates from blood cultures and colonization sites had identical antimicrobial susceptibility patterns. Emphasis on handwashing, careful preparation and administration of infusates, and aseptic technique for catheter insertion, maintenance, and manipulation was temporally associated with resolution of the epidemic. CONCLUSIONS: This outbreak was probably due to infusion therapy practices that led to BSI in nursery patients colonized with K pneumoniae. Both catheter-related infections and extrinsic contamination of infusates may have occurred. Hospital personnel should be aware of their potential to spread nosocomial pathogens from person to person and should implement Centers for Disease Control and Prevention recommendations to decrease nosocomial BSIs.     

Impact of influenza on acute cardiopulmonary hospitalizations in pregnant women

This study sought to quantify influenza-related serious morbidity in pregnant women, as measured by hospitalizations for or death from selected acute cardiopulmonary conditions during predefined influenza seasons. The study population included women aged 15-44 years who were enrolled in the Tennessee Medicaid program for at least 180 days between 1974 and 1993. In a nested case-control study, 4,369 women with a first study event during influenza season were compared with 21,845 population controls. The odds ratios associated with study events increased from 1.44 (95% confidence interval (CI) 0.97-2.15) for women at 14-20 weeks' gestation to 4.67 (95% CI 3.42-6.39) for those at 37-42 weeks in comparison with postpartum women. A retrospective cohort analysis, which controlled for risk factors identified in the case-control study, identified 22,824 study events during 1,393,166 women-years of follow-up. Women in their third trimester without other identified risk factors for influenza morbidity had an event rate of 21.7 per 10,000 women-months during influenza season. Approximately half of this morbidity, 10.5 (95% CI 6.7-14.3) events per 10,000 women-months, was attributable to influenza. Influenza-attributable risks in comparable nonpregnant and postpartum women were 1.91 (95% CI 1.51-2.31) and 1.16 (95% CI -0.09 to 2.42) per 10,000 women-months, respectively. The data suggest that, out of every 10,000 women in their third trimester without other identified risk factors who experience an average influenza season of 2.5 months, 25 will be hospitalized with influenza-related morbidity.     

Indoor radon exposure and risk of lung cancer: a nested case-control study in Finland

BACKGROUND: Inhaled radon has been shown to cause lung cancer among underground miners exposed to very high radon concentrations, but the results regarding the effects of residential radon have been conflicting. PURPOSE: Our aim was to assess the effect of indoor radon exposure on the risk of lung cancer. METHODS: To investigate this effect, a nested case-control study was conducted in Finland. The subjects of the study were the 1973 lung cancer case patients (excluding patients with cancers of the pleura) diagnosed from January 1, 1986, until March 31, 1992, within a cohort of Finns residing in the same one-family house from January 1, 1967, or earlier, until the end of 1985 and 2885 control subjects identified from the same cohort and matched by age and sex. In September 1992, a letter was sent to all study subjects or proxy respondents explaining the purpose and methods of the study. After giving informed consent, the study participants were asked to fill out a questionnaire on smoking habits, occupational exposures, and other determinants of lung cancer risk and radon exposure. The odds ratio (OR) of lung cancer was estimated from matched and unmatched logistic regression analyses relative to indoor radon concentration assessed by use of a 12-month measurement with a passive alpha track detector. RESULTS. Five hundred seventeen case-control pairs were used in the matched analysis, and 1055 case subjects and 1544 control subjects were used in the unmatched analysis. The OR of lung cancer for indoor radon exposure obtained from matched analysis was 1.01 (95% confidence interval [CI] = 0.94-1.08) per 2.7 pCi/L (100 Bq m-3) after adjustment for the cigarette smoking status, intensity, duration, and age at commencement of smoking by subjects. For indoor radon concentrations 1.4-2.6, 2.7-5.3, 5.4-10.7, and 10.8-34.5 pCi/L (50-99, 100-199, 200-399, and 400-1277 Bq m-3, respectively), the matched ORs were 1.03 (95% CI = 0.84-1.26), 1.00 (95% CI = 0.78-1.29), 0.91 (95% CI = 0.61-1.35), and 1.15 (95% CI = 0.69-1.93), respectively, relative to the concentration below 1.4 pCi/L (0-49 Bq m-3). The unmatched analysis yielded similar results with somewhat smaller CIs. In the analyses stratified by age, sex, smoking status, or histologic type of lung cancer, no statistically significant indications of increased risk of lung cancer related to indoor radon concentration were observed for any of the subgroups. CONCLUSIONS: Our results do not indicate increased risk of lung cancer from indoor radon exposure. IMPLICATION: Indoor radon exposure does not appear to be an important cause of lung cancer.     

The association between the purchase of a handgun and homicide or suicide

OBJECTIVES: The purpose of this study was to determine whether purchase of a handgun from a licensed dealer is associated with the risk of homicide or suicide and whether any association varies in relation to time since purchase. METHODS: A case-control study was done among the members of a large health maintenance organization. Case subjects were the 353 suicide victims and 117 homicide victims among the members from 1980 through 1992. Five control subjects were matched to each case subject on age, sex, and zip code of residence. Handgun purchase information was obtained from the Department of Licensing. RESULTS: The adjusted relative risk of suicide was 1.9 (95% confidence interval [CI] = 1.4, 2.5) for persons with a history of family handgun purchase from a registered dealer. The adjusted relative risk for homicide, given a history of family handgun purchase, was 2.2 (95% CI = 1.3, 3.7). For both suicide and homicide, the elevated relative risks persisted for more than 5 years after the purchase. CONCLUSIONS: Legal purchase of a handgun appears to be associated with a long-lasting increased risk of violent death.     

Maternal flu, fever, and the risk of neural tube defects: a population-based case-control study

Results of clinical and epidemiologic studies have shown an increased risk for neural tube defects (NTD) in infants whose mothers were exposed to heat during pregnancy. However, the risk for NTD in infants whose mothers had influenza during pregnancy has not been well studied. This population-based case-control study of infants born in metropolitan Atlanta, Georgia, from 1968 through 1980 included 385 infants with NTD, 3,647 infants with other birth defects, and 2,676 infants without birth defects. Of the 385 mothers of case infants, 31 reported having a 2-day or longer episode of flu with fever from 1 month before through 3 months after conception (odds ratio (OR) = 3.0; 95% confidence interval (CI) 1.9-4.7). Infants of mothers who took medications for their episodes of flu with fever had an even higher risk for NTD (OR = 4.3, 95% CI 2.6-7.1). When mothers of infants with birth defects other than NTD were used as controls, an increased risk of NTD remained for flu with fever (OR = 1.7, 95% CI 1.1-2.5). There was no increased risk for NTD among the infants of mothers who reported fever from causes other than flu. Because of the heterogeneity of maternal flu, the individual contributions of infection, fever, and medications remain difficult to disentangle.     

The efficacy and cost effectiveness of vaccination against influenza among elderly persons living in the community

BACKGROUND: Despite recommendations for annual vaccination against influenza, more than half of elderly Americans do not receive this vaccine. In a serial cohort study, we assessed the efficacy and cost effectiveness of influenza vaccine administered to older persons living in the community. METHODS: Using administrative data bases, we studied men and women over 64 years of age who were enrolled in a large health maintenance organization in the Minneapolis-St. Paul area. We examined the rate of vaccination and the occurrence of influenza and its complications in each of three seasons: 1990-1991, 1991-1992, and 1992-1993. Outcomes were adjusted for age, sex, diagnoses indicating a high risk, use of medications, and previous use of health care services. RESULTS: Each cohort included more than 25,000 persons 65 years of age or older. Immunization rates ranged from 45 percent to 58 percent. Although the vaccine recipients had more coexisting illnesses at base line than those who did not receive the vaccine, during each influenza season vaccination was associated with a reduction in the rate of hospitalization for pneumonia and influenza (by 48 to 57 percent, P < or = 0.002) and for all acute and chronic respiratory conditions (by 27 to 39 percent, P < or = 0.01). Vaccination was also associated with a 37 percent reduction (P = 0.04) in the rate of hospitalization for congestive heart failure during the 1991-1992 season, when influenza A was epidemic. The costs of hospitalization for all types of illness studied were lower in the vaccinated group during 1991-1992 (range of reduction, 47 to 66 percent; P < 0.005) and for acute and chronic respiratory conditions and congestive heart failure in 1990-1991 (reductions of 37 percent and 43 percent, respectively; P < or = 0.05). Direct savings per year averaged $117 per person vaccinated (range, $21 to $235), with cumulative savings of nearly $5 million. Vaccination was also associated with reductions of 39 to 54 percent in mortality from all causes during the three influenza seasons (P < 0.001). CONCLUSIONS: For elderly citizens living in the community, vaccination against influenza is associated with reductions in the rate of hospitalization and in deaths from influenza and its complications, as compared with the rates in unvaccinated elderly persons, and vaccination produces direct dollar savings.     

Gallstones and diabetes: a case-control study in a free-living population sample

Data on the association between cholelithiasis and diabetes often are controversial and are mostly based on autopsies or on hospital series. Therefore, we designed a case-control study to determine the prevalence of diabetes mellitus in a group of subjects with gallstones or having undergone cholecystectomy (cases) and compared these with a control group of subjects without gallstones, selected during an epidemiological study performed on a free-living population sample. The subjects were matched for sex, age, and body mass index. We enlisted 336 cases and 336 controls, aged 30 to 69 years. All subjects with fasting glycemic levels of < 140 mg/dL and without a documented history of diabetes were submitted to a simplified oral glucose tolerance test (OGTT). All subjects who underwent OGTT were classified according to the National Diabetes Data Group (NDDG) criteria. The prevalence of diabetes in the subjects affected by gallstone disease was significantly higher than that in controls (11.6% vs. 4.8%; odds ratio [OR], 2.55; 95% confidence interval [CI], 1.39-4.67). Diabetes was more frequent in subjects with gallstone disease than in the control group, even according to sex (18.3% vs. 9.9% for men: OR, 2.03; 95% CI, 0.99-4.2; 9.3% vs. 2.6% for women: OR, 3.85; 95% CI, 1.4-10.6). We conclude that an altered glucose metabolism may increase the risk of developing cholelithiasis in certain subjects.     

Human immunodeficiency virus infection and stroke in young patients

OBJECTIVE: To determine the association between human immunodeficiency virus (HIV) infection and stroke among young persons. DESIGN: Retrospective case-control study. SETTING: Large, inner-city public hospital. PARTICIPANTS: All patients aged 19 to 44 years with a diagnosis of stroke, whose HIV status was determined, admitted from January 1990 through June 1994. Controls matched for age and sex were selected from patients who were admitted during the same period for status asthmaticus whose HIV status was known. MAIN OUTCOME MEASURE: The associations of HIV infection with all strokes and with cerebral infarction, after adjustment for other cerebrovascular risk factors, were evaluated by Mantel-Haenszel stratified analyses. The subtypes and causes of stroke in HIV-infected patients were compared with HIV-seronegative patients. RESULTS: The HIV infection was associated with stroke (odds ratio [OR], 2.3; 95% confidence interval [CI], 1.0-5.3) and cerebral infarction (OR, 3.4; 95% CI, 1.1-8.9), after adjustment for other cerebrovascular risk factors. Among patients with stroke, cerebral infarction was more frequent in HIV-infected patients than in HIV-seronegative patients (20 [80%] of 25 vs 48 [56%] of 88, P = .04). The frequency of cerebral infarctions associated with meningitis (P < .001) and protein S deficiency (P = .06) was higher in HIV-infected patients than in seronegative patients. CONCLUSIONS: Our study suggests that HIV infection is associated with an increased risk of stroke, particularly cerebral infarction in young patients. This risk is probably mediated by increased susceptibility of HIV-infected patients to meningitis and protein S deficiency.     

Efficacy of a two-component acellular pertussis vaccine in infants

OBJECTIVE: This case-control study investigated the protective efficacy against pertussis of three doses of a two-component acellular pertussis vaccine (manufactured by Biken in Japan) combined with diphtheria and tetanus toxoids (manufactured by Connaught Laboratories in the US) in infants. METHODS: A case-control study was performed in 63 pediatric practices in Germany. Prospective recruitment of 16,780 infants ages 6 to 17 weeks took place between February, 1993, and July, 1994. According to parental choice infants received either Biken acellular pertussis vaccine combined with diphtheria and tetanus toxoids (DTacP) (74.6%) at approximately 2, 4 and 6 months of age, or a licensed German diphtheria-tetanus toxoids-whole cell pertussis vaccine (10.9%), diphtheria-tetanus toxoids vaccine (12.5%) or no vaccine (2.0%). Prospective surveillance of pertussis cases between February, 1993, and May, 1995, was accomplished by culturing all infants < or =2 years of age presenting with cough > or = 7 days. A pertussis case was defined as any cough of 21 days or longer plus a positive Bordetella pertussis culture or household contact exposure. RESULTS: We identified 241 pertussis cases prospectively by 11,017 B. pertussis cultures and 949 controls matched for age were selected from the same pediatric practices. Medical history and demographic and vaccine status data were collected from each case and for four controls. Data were analyzed through conditional logistic regression taking into account individual matching and adjusting for potential confounding variables. DTacP combined with diphtheria and tetanus toxoids vaccine was 82% protective (95% confidence interval, 68 to 90), diphtheria-tetanus toxoids-whole cell pertussis vaccine was 96% protective (95% confidence interval, 78 to 99). Protection against typical B. pertussis infection characterized by paroxysmal cough lasting > or =21 days was 96% (95% confidence interval, 87 to 99) for DTacP and was 97% (95% confidence interval, 79 to 100) for diphtheria-tetanus toxoids-whole cell pertussis vaccine. Adjustment for potentially confounding variables did not change the results significantly. CONCLUSIONS: Three doses of the two-component acellular pertussis vaccine protected infants against pertussis disease during the period before the recommended booster vaccination. For typical pertussis disease as defined by the WHO efficacy was high and similar to that of a licensed German diphtheria-tetanus toxoids-whole cell pertussis vaccine.     

病例对照Meta分析显示男性乳腺癌与女性乳腺癌预后相同

Objective: Male breast cancer (MBC) is a rare disease, and studies to compare the prognosis between the MBC and female breast cancer (FBC) available now were case-control studies and population-based studies, however, with controversial outcomes. To further investigate whether sex affects the prognosis of breast cancer, we performed a meta-analysis based on all the peered papers. Methods: The PubMed database was screened. Subsequently, the hazard ratios (HRs) for overall survival (OS) and disease special survival (DSS), were pooled using the Review Manager 5.0 package. Results: This study comprised of 254 MBC and 733 FBC patients enrolled in six case-control studies. There was no statistically significant heterogeneity among the trials for either outcome variable. The pooled HR showed that there was no significant difference in 5-year or 10-year DSS (HR: 1.25, 95% CI: 0.76-2.08; HR: 1.04, 95% CI: 0.66-1.59) and 5-year or 10-year OS (HR: 0.76, 95%CI: 0.51-1.14; HR: 0.74, 95% CI: 0.54-1.02) between MBCs and FBCs. Conclusion: MBC and FBC with similar prognosis are found in this meta-analysis based on only case-control studies which matched main potential prognostic factors such as age, clinical stage, and time at diagnosis.     

Oral cancer risk in relation to sexual history and evidence of human papillomavirus infection

BACKGROUND: Experimental models and analyses of human tumors suggest that oncogenic, sexually transmittable human papillomaviruses (HPVs) are etiologic factors in the development of oral squamous cell carcinoma (SCC). We conducted a population-based, case-control study to determine whether the risk of this cancer is related to HPV infection and sexual history factors. METHODS: Case subjects (n = 284) were 18-65-year-old residents of three counties in western Washington State who were newly diagnosed with oral SCC from 1990 through 1995. Control subjects (n = 477) similar in age and sex were selected from the general population. Serum samples were tested for HPV type 16 capsid antibodies. Exfoliated oral tissue collected from case and control subjects and tumor tissue from case subjects were tested for HPV DNA. Odds ratios (ORs) were calculated after adjusting for age, sex, cigarette smoking, and alcohol consumption. RESULTS: Among males only, oral SCC risk increased with self-reported decreasing age at first intercourse, increasing number of sex partners, and a history of genital warts. Approximately 26% of the tumors in case subjects contained HPV DNA; 16.5% of the tumors contained HPV type 16 DNA. The prevalence of oncogenic HPV types in exfoliated oral tissue was similar in case and control subjects. The ORs for HPV type 16 capsid seropositivity were 2.3 (95% confidence interval [CI] = 1.6-3.3) for all oral SCCs and 6.8 (95% CI = 3.0-15.2) for oral SCCs containing HPV type 16 DNA. The joint association of cigarette smoking and HPV type 16 capsid seropositivity with oral SCC (OR = 8.5; 95% CI = 5.1-14.4) was stronger than predicted from the sum of individual associations with current smoking (OR = 3.2; 95% CI = 2.0-5.2) and seropositivity (OR = 1.7; 95% CI = 1.1-2.6). CONCLUSIONS: HPV type 16 infection may contribute to the development of a small proportion of oral SCCs in this population, most likely in combination with cigarette smoking.     

Epidemiologic determinants of endometriosis: a hospital-based case-control study

PURPOSE: Risk factors for endometriosis were identified through data obtained from a case-control study at Brigham and Women's Hospital in Boston, Massachusetts. METHODS: Cases were 50 women with infertility-associated endometriosis. The primary control group consisted of 89 fertile women without endometriosis, and an alternate control group consisted of 47 infertile women without endometriosis. RESULTS: The risk of endometriosis was positively associated with height (OR), 2.8 per 10 cam increase; 95% confidence interval (CI), 1.4-5.6) and inversely associated with weight (OR, 0.7 per 10 kg increase; 95% CI, 0.5-1.0) and body mass index (OR, 0.7 per 5 kg/m2 increase; 95% CI, 0.4-1.1). We observed an inverse association with exercise (OR, 0.6; 95% CI, 0.3-1.5), but the effect was limited to women who exercised > or = 4 hours per week (OR, 0.4; 95% CI, 0.2-1.2). Endometriosis was not associated with either smoking or alcohol consumption. CONCLUSIONS: Our findings suggest that the fertility status of controls can strongly influence associations seen with menstrual characteristics. This study is one of few to address the issue of control selection for a case-control study of endometriosis. Specifically, potential problems encountered using fertile and infertile control women are examined and discussed.     

Effectiveness of bacillus of Calmette-Guerin (BCG) vaccination against tuberculous meningitis: a case-control study

A hospital-based pair-matched case-control study was carried out at Government Medical College Hospital, Nagpur to estimate the effectiveness of bacillus of Calmette-Guerin (BCG) vaccination against tuberculous meningitis. The study included 92 cases of tuberculous meningitis in the age group of 0-12 years and equal number of controls, matched for age, sex and socio-economic status. The protective effectiveness and prevented fraction were higher for the subjects in the age group of 0-6 years, males and subjects from upper strata of socio-economic class. The overall vaccine effectiveness and prevented fraction were estimated to be 86.54% (70.38-93.88%) and 65.54% (39.22-80.64%) respectively. Results of this study thus indicated that BCG vaccination was highly effective against tuberculous meningitis and played significant role in its prevention, in this population.     

Occupational exposures and amyotrophic lateral sclerosis. A population-based case-control study

This population-based case-control study was conducted in three countries in western Washington State to evaluate associations between workplace exposures and the risk of amyotrophic lateral sclerosis (ALS). Cases (n = 174) were all newly diagnosed with ALS by neurologists during 1990-1994, and controls (n = 348), who were matched according to age (+/-5 years) and sex, were identified via random-digit dialing or Medicare enrollment files. Four industrial hygienists blindly assessed detailed lifetime job histories for exposures to metals, solvents, and agricultural chemicals. Case-control comparisons were made for jobs held between 15 years of age and 10 years prior to the cases' dates of diagnosis. After adjustment for age and education, ever exposure to agricultural chemicals was associated with ALS (odds ratio (OR) = 2.0, 95% confidence interval (CI) 1.1-3.5); this association was observed separately in men (OR = 2.4, 95% CI 1.2-4.8) but not in women (OR = 0.9, 95% CI 0.2-3.8). Among men, the odds ratio for low exposure to agricultural chemicals (below the median level for exposed controls) relative to no exposure was 1.5 (95% CI 0.4-5.3), and for high exposure, it was 2.8 (95% CI 1.3-6.1) (p for trend = 0.03). Similar analyses based on the panel's assessment of exposures to metals and solvents showed no associations. These findings suggest an association between ALS and agricultural chemicals in men.     

Breast cancer among women exposed to polybrominated biphenyls

We conducted a nested case-control study with 1,925 women enrolled in a polybrominated biphenyl (PBB) registry to examine the association between breast cancer and serum PBBs. Twenty women who developed breast cancer were matched to 290 control subjects on sex, race, and age. Women with serum PBB levels of 2.0-3.0 parts per billion (ppb) [odds ratio (OR) = 3.5; 95% confidence interval (CI) = 0.9-13] or 4.0 ppb or greater (OR = 3.1; 95% CI = 0.8-12) had a higher estimated risk for breast cancer than women with less than 2.0 ppb. The odds ratios were unchanged when available breast cancer risk factors were included in the analysis.     

Are spouses of patients with hypertension at increased risk of having hypertension? A population-based case-control study

BACKGROUND: Studies of couples, who tend to share an environment but are genetically dissimilar, can shed light on the contribution of environmental factors to hypertension. There has been renewed interest in these environmental factors following the re-analysis of the INTERSALT study. AIM: To determine whether patients whose spouses have hypertension are at increased risk of hypertension, using a population-based case-control study. METHOD: The total study population consisted of all 3923 patients over 30 years old registered with one general practice. Male cases with hypertension were matched to male controls without hypertension. Female cases with hypertension were matched to female controls without hypertension. The variables were: diagnosed hypertension; having a spouse with diagnosed hypertension; age; sex; weight; height; body-mass index; couple status; diabetes; and systolic and diastolic blood pressure readings. RESULTS: On multivariate analysis, when age, body-mass index, diabetes, couple status, and having a blood pressure reading were included, men whose spouses had hypertension had a two-fold increased risk of hypertension (adjusted odds ratio (OR) 2.24; 95% CI 1.77-2.72; P = 0.001). Similarly, on multivariate analysis, women whose spouses had hypertension had a two-fold increased risk of hypertension (adjusted OR = 2.23; 95% CI 1.75-2.72; P = 0.001). The risk for both male and female subjects persisted after adjustment for other variables. There was a significant correlation between systolic (r = 0.41; P < 0.0001) and diastolic (r = 0.25; P < 0.0001) blood pressures between spouse pairs. CONCLUSION: The independent association between having a spouse with hypertension and increased risk of hypertension supports the view that there are significant environmental factors in the aetiology of hypertension. The finding has implications for the screening and treatment of hypertension in primary care.     

Blood transfusion, smoking, and obesity as risk factors for the development of rheumatoid arthritis: results from a primary care-based incident case-control study in Norfolk, England

OBJECTIVE: To examine a range of demographic, social, and clinical risk factors for the development of rheumatoid arthritis (RA). METHODS: Population-based case-control study in Norfolk, England, involving adult patients, ages 18-70, with an inflammatory polyarthritis of <12 months' duration who were recruited from the Norfolk Arthritis Register. Controls, matched for sex and date of birth, were selected from the primary care register of the Norwich Health Authority. Both cases and controls completed identical self-administered questionnaires. Matched analysis of the 165 case-control sets was conducted for the whole group and for the subset in which the cases satisfied the 1987 American College of Rheumatology criteria for RA. RESULTS: The controls were of higher socioeconomic status than the cases. This was probably due to response bias. Having a body mass index > or =30 was associated with an adjusted odds ratio (OR) of 3.74 for developing RA (95% confidence interval [95% CI] 1.14-12.27). RA was also associated with a history of blood transfusion (OR 4.83, 95% CI 1.29-18.07). Even after correcting for social class, a history of having ever smoked was associated with a higher risk of developing RA (OR 1.66, 95% CI 0.95-3.06). There was no difference between cases and controls in previous exposure to childhood infections, certain surgical procedures, or reproductive history variables. CONCLUSION: RA has a number of potential environmental triggers, including smoking, obesity, and blood transfusion.     

Optimization of energy-dependent processes in mitochondria from rat liver and brain after inhalation of negative air ions

BACKGROUND: Bone cancers in children are serious and highly fatal conditions, yet relatively little is known about their causes or methods of prevention. METHODS: The relationship between parental occupation and bone cancer in offspring was explored in a case-control study. Cases were identified from the Ontario Cancer Registry; population-based controls were matched on sex and age. Data were collected from their parents through the use of a mailed self-administered questionnaire. RESULTS: The odds ratio estimates (OR) for bone cancer were elevated for fathers in the social sciences (OR = 2.5, 95% confidence interval [CI]: 0.7-8.4). Risk of Ewing's sarcoma was significantly high among children with fathers in social sciences (OR = 6.2, 95% CI: 1.6-24.5) and mothers in teaching (OR = 3.1, 95% CI: 1.1-8.7) or farming (OR = 7.8, 95% CI: 1.9-31.7). Osteosarcoma risk was increased for fathers in farming (OR = 2.1, 95% CI: 0.8-5.7), and mothers in managerial and administrative work (OR = 2.3, 95% CI: 0.6-8.1), and product fabricating, assembling, and repairing (OR = 2.0, 95% CI: 0.6-7.2). CONCLUSIONS: Certain methodological problems plague studies of bone cancer in children (e.g. small studies, low statistical power, analysis of multiple occupational categories, difficulty in identifying specific carcinogenic agents). These associations require further investigation, especially as elevated risks have been reported previously for agricultural occupations.     

Evaluation of live, cold-adapted influenza A and B virus vaccines in elderly and high-risk subjects

We have evaluated the use of live cold-adapted influenza A and B virus vaccines in the elderly. Cold-adapted influenza A and B virus vaccines are safe and modestly immunogenic in individuals over 65 years of age. However, our studies and those of other groups have shown that immune response to cold-adapted vaccines in this age group are modest. Administration of combined cold-adapted influenza A and inactivated influenza vaccine has resulted in slightly higher frequencies of local and systemic humoral immune responses than inactivated vaccine alone in some, but not all, studies. In a double-blind field trial conducted in nursing homes over a 3 year period, combined cold-adapted influenza A (H3N2) and trivalent inactivated influenza vaccine resulted in a 60% decrease (95% CI, 18-82%) in the rate of laboratory documented influenza A compared with inactivated vaccine alone. Further studies of multivalent cold-adapted influenza vaccines used in combination with inactivated vaccine should be performed.