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PubMed1991

[Sinonasal cancer and occupation: a multicenter case-control study].

A case-control study was conducted to examine occupational risk factors for sinonasal cancer. 207 cases and 409 controls (323 cancer hospital controls and 86 controls selected from lists provided by the cases) were included in the study. All cases and controls were interviewed by specially trained physicians. Detailed information on occupational history was collected, in addition to other potential risk factors for nasal cancer. Results are presented for two histologic types: adenocarcinoma and squamous cell carcinoma. Among males, the risk of adenocarcinoma was significantly elevated for carpenter and joiners (OR = 17.7) and other woodworkers (OR = 26.9). A significant increase in risk of squamous cell cancer (OR = 2.5) and a moderate increase in risk of adenocarcinoma (OR = 1.7; NS) were noted for construction workers. Among females, an excess risk of squamous cell carcinoma was associated with employment in textile industry (OR = 2.9). Elevated risks of squamous cell cancer were observed for farm workers of both sexes (males: OR = 2.2; females OR = 4.9).

Adenocarcinoma↗

PubMed1992

Risk factors for fatal venous thromboembolism in young women: a case-control study.

A case-control study of fatal venous thromboembolism in young women is described. Sixty women aged between 16 and 39 who died from thromboembolism in England and Wales between 1986 and 1988 were included in the study. Two living controls matched for age and marital status were sought from the records of the general practitioner with whom each case was registered. Some 115 controls were included in the study. The cases had a significantly higher prevalence of a history of major illness, particularly thrombotic episodes, than the controls. The odds ratio (OR) of a fatal thromboembolism in women who had a history of venous thrombosis was 4.0 (95% Cl: 1.4-11.5). There was also a significantly higher frequency of a recent operation or accident amongst the cases than the controls (OR = 11.1, 95% Cl: 1.3-92.5). There was no significant excess or oral contraceptive use amongst the cases. The overall OR associated with current use of oral contraceptives was 1.6 (95% Cl: 0.7-3.4), while the corresponding OR for 'idiopathic' diseases was 2.1 (95% Cl: 0.8-5.2). These risks are considerably smaller than those observed in previous studies. The observed risk may be low because the dosage of oestrogen in modern oral contraceptive preparations has been reduced, but it may also be because the cases of fatal venous thromboembolism included in this study represent only a small proportion of all cases of venous thrombeombolism; a disease which is rarely fatal in young women. These results cannot necessarily be extrapolated to nonfatal venous thromboembolism.

Adolescent↗

PubMed1992

Fatal stroke and use of oral contraceptives: findings from a case-control study.

A case-control study of women less than 40 years of age in England and Wales was performed to evaluate the risk of fatal stroke associated with the use of the newer, low-dose oral contraceptives. Included were 296 cases with subarachnoid hemorrhage, 105 cases with other hemorrhagic stroke, and 21 cases with occlusive stroke, all of which occurred during 1986-1988. Two living controls per case, matched for age and marital status, were chosen from the general practice lists. The power of the study was such that the minimum significant increased relative risk of subarachnoid hemorrhage associated with ever having used oral contraceptives that could have been detected with 90% certainty was 1.6; the equivalent value for occlusive stroke was 28.4. Relative risk was estimated by conditional logistic regression allowing for matching. The adjusted relative risk of subarachnoid hemorrhage associated with oral contraceptives was estimated to be 1.1 (95% confidence interval (CI) 0.6-1.9) for current use and 1.3 (95% CI 0.9-1.8) for ever use, while the equivalent relative risk of an occlusive stroke associated with ever use was 4.4 (95% CI 0.8-24.4). Oral contraceptive use may be associated with a small increase in the risk of subarachnoid hemorrhage. These data are consistent with a substantial increase in the risk of occlusive stroke associated with oral contraceptive use.

Adolescent↗

PubMed1989

Occupation and bladder cancer in Spain: a multi-centre case-control study.

A case-control study on bladder cancer was carried out in four regions of Spain. The study included 497 cases (438 males and 59 females), 583 hospital controls and 530 population controls matched by sex, age and residence. The present paper reports the results of the analyses on occupational history. Among men, an increased risk of bladder cancer was found for textile workers (OR = 1.97, 95% CL 1.2-3.3), mechanics and maintenance workers (OR = 1.86, 95% CL 1.2-2.8), workers in the printing industry (OR = 2.06, 95% CL 1.0-4.3) and for managers (OR = 2.03, 95% CL 1.2-3.5). The risk was highest among those first employed in the textile industry before the age of 25 and prior to 1960. Among mechanics the risk was highest for those who started after the age of 25 and later than 1960. The OR for smokers who had also been employed in one of the high risk occupations was 7.82 (95% CL 4.4-14.0) which is compatible with a multiplicative effect of joint exposure to tobacco and occupational hazards.

Aged↗

PubMed1990

Rotavirus diarrhoea in Apache children: a case-control study.

A case-control study of rotavirus diarrhoea in Apache children up to two years old was conducted at the White Mountain Apache reservation from 1 May through 15 December 1985 to identify risk factors for rotavirus diarrhoea. The mothers of fifty cases, forty-five hospital controls and twenty-five neighbourhood controls participated in this study. Exposure to other children with diarrhoea stood out as the single most important factor for acquiring rotavirus diarrhoea (Odds ratio = 14.0). Other significant risk factors were living in homes with septic tanks and in homes with 'poor environmental sanitation.'. Minimizing contacts of children with diarrhoea therefore would be the most effective measure in preventing the spread of this disease in the community.

Arizona↗

PubMed1991

[Risk factors of intracerebral hemorrhage. A case-control study].

In case-control study of 53 cases of intracerebral hemorrhage diagnosed by CT scan. Significant risk factors were chronic alcoholism (P less than 0.05), history of hypertension, fundus arteriosclerosis, aorta atherosclerosis, electrocardiogram (ECG) abnormalities, high blood triglycerides, hyperviscosity, hyper-plasma viscosity, hyperfibrinogenemia and increased VWF (P less than 0.01 or P less than 0.001). After principal component analysis hyperviscosity, hypertension, coronary heart disease, ECG abnormalities, chronic alcoholism, and increased VWF were selected as primary risk factors (accumulative contributed rates 59.84%). Alcoholism, EXG abnormalities, aorta atherosclerosis correlates significantly with haemorheology.

Aged↗

PubMed1989

[Spatial identification of an excess of cerebral tumors in a highly industrialized small area: results of a case-control study].

A case-Control Study for the association between Central Nervous System Malignancies and residence in a small area within the municipality of Campi Bisenzio (Florence, Italy) has been performed following a spontaneous reporting of three cases of brain cancer. All incident cases of SNC tumours diagnosed in the period 1973-82 with histological or radiological confirmation among residents in the study area are recruited as cases. Five controls for each case, matched by sex and age (+ - 1 year), are randomly chosen from demographic files in the municipality. The residential history for each subject enrolled in the study is recorded from the same demographic files. The relative risk for ever resident in the 46-50 electoral sections relative to never resident was 7.33 (C.I. 95% 2.6-20.3). A trend for duration of residence was also relevant (less than 5 years RR = 2.1, 5-10 years RR = 8.4, more than 10 years RR = 11.3; chi-square for trend = 41 p = 0.00002).

Adolescent↗

PubMed1989

A computer program for incidence density sampling of controls in case-control studies nested within occupational cohort studies.

A nested case-control study is a case-control study performed with a cohort study. The nested case-control design is useful because the number of study subjects for whom risk factor information is needed is smaller than in the original cohort study. The approach is especially helpful when collection of data is expensive or time consuming, as when it is necessary to contact subjects or next of kin. Selection of controls in nested case-control studies is best performed with a method called "incidence density" sampling. An approach to incidence density sampling that yields a valid estimate of the rate ratio is sampling without replacement from noncases at the time of case occurrence. To implement this approach, a system of computer programs was written that randomly selects a user defined number of controls for each case. The case-control data produced by this program can be analyzed by conditional logistic regression.

Cohort Studies↗

PubMed1991

Principles behind practice. 7. Case-control studies.

The case-control study is often a very simple, cheap and quick way to test the hypothesis that a particular factor causes a disease or that a particular treatment is helping patients who receive it. There also seems to be an inherent logic in comparing patients and well people to see how they differed in the past, or in comparing those who did and did not survive a certain illness to see how their treatment differed. Despite these appealing features, the case-control approach is subject to a number of pitfalls. These can usually be avoided by an appropriately designed study, and by careful collection and analysis of the data. Even so, the results of a case-control study are a lower order of evidence than those produced from a properly conducted randomised controlled trial.

Bias↗

PubMed1990

Risk factors for in situ cervical cancer: results from a case-control study.

A case-control study of 293 patients with in situ cervical cancer and 801 community controls was conducted between 1982 and 1984 in five geographic areas in the United States. Relative risk (RR) was elevated among women reporting multiple sexual partners (RR for greater than or equal to 5 partners = 5.0), a history of an abnormal Papanicolaou smear (RR = 5.0), interval since last Papanicolaou smear (RR for greater than or equal to 10-year interval versus 0- to 2-year interval = 4.1), use of oral contraceptives (RR for greater than or equal to 10 years use = 1.4), a history of nonspecific genital infection (RR = 2.6), and smoking (RR for current smokers = 1.9). Risk was low among diaphragm users (RR for greater than 2 years use = 0.5). Neither age at first coitus nor number of births was predictive of risk of in situ disease. Comparisons between this analysis and risk factors previously identified for invasive cervical cancer in this same study indicate that the risk factors were quite similar.

Adult↗

PubMed1991

The protective effect of measles vaccine under routine vaccination conditions in Dar es Salaam, Tanzania: a case-control study.

A case-control study was conducted to determine the protective effect of measles vaccine under routine vaccination conditions in Dar es Salaam, Tanzania. A total of 172 cases of measles were obtained over two six-week periods from hospitals likely to admit such cases in the city and their mothers interviewed using a questionnaire that had been developed for the purpose. In addition, each case was matched to four controls for age, sex and place of residence and their mothers were also interviewed using the same questionnaire as for the cases. Vaccination status of the cases and the controls was ascertained by asking the mothers as well as obtaining vaccination information from the Mother-and-Child or Road-to-Health (MCH) clinic cards normally issued to mothers at first vaccination of their children. The overall protective effect of measles vaccine in all age groups studied was found to be 54% (95% confidence limits (CL)36%-67%) when mothers' recall for vaccination status was used. This level of protection was considered to be low compared with the efficacy of the vaccine under experimental conditions in controlled trials previously reported. However when MCH Clinic cards were used to ascertain vaccination status the protective effect rose to as high as 96% (95% CL 83%-99%). Potential biases in the study design and their role in masking or exaggerating the vaccine efficacy are discussed. It was therefore concluded that the protective effect of measles vaccine under routine vaccination conditions prevailing in Dar es Salaam region at the time of this study was as high as observed under experimental conditions when ascertainment of vaccination status was record-based. The study therefore recommended that, whenever in doubt about vaccine efficacy, simple study designs like the case-control method should be used to quickly evaluate vaccine efficacy by utilizing record-based vaccination status ascertainment methods.

Case-Control Studies↗

PubMed1985

Risk factors associated with the acquisition of sleeping sickness in north-east Zambia; a case-control study.

A case-control study identified 59 cases of Rhodesian sleeping sickness in the northern Luangwa valley of Zambia together with age- and sex-matched nearest neighbour and hospital controls. Birth outside the trypanosomiasis endemic area was not shown to increase the risk of acquiring sleeping sickness. Significantly more cases under the age of 20 years had lived outside the endemic area compared with neighbour controls, although this was not true for those over 20 years old. Ethnic group and main occupation did not differ between cases and neighbour controls. Fishing as an auxiliary occupation increased the risk infection. Members of the United Church of Zambia had a relative risk of acquiring trypanosomiasis twice as great as other religious groups, perhaps because their scattered churches involve more walking through tsetse-infected bush. Sleeping sickness cases said that there were zebras near their village significantly more often than controls, although zebras are not usually considered a likely source of infection. In a preliminary study there was no difference in blood groups or haemoglobin genotype between cases and controls.

Adolescent↗

PubMed1991

Risk factors of nonmelanoma skin cancer in Ragusa, Sicily: a case-control study.

A case-control study on 133 consecutive incident cases of nonmelanoma skin cancer registered by Cancer Registry of Ragusa (Sicily) was carried out in order to evaluate the correspondence between risk factors observed in other geographic areas with those of a Latin country with a strong solar exposure. A multivariate analysis showed that family history of skin cancer, cancer-related cutaneous diseases, fair skin color, residence more than 400 meters above sea level, and prolonged solar exposure without protection, significantly and independently increase the risk of skin cancer. Ease of suntanning was an important protective factor. Solar exposure was a stronger risk factor for squamous cell than for basal cell cancer. The results of the study enable us to identify a high risk group of people to whom simple methods of protection against solar exposure may be suggested to reduce the risk of skin cancer.

Adult↗

PubMed1991

Colorectal polyps, diet, alcohol, and family history of colorectal cancer: a case-control study.

A case-control study was conducted in Melbourne, Australia. Cases (n = 49) were patients who had one or more histologically confirmed adenomatous polyps larger than 1 cm in diameter previously removed by endoscopy. In both the cases and the community controls (n = 727), previous diet, alcohol consumption, and family history of colorectal cancer in near relatives were investigated. The family history rate of colorectal cancer was similar in the two groups. Those with adenomatous polyps were found to have a low fiber/vegetable intake (p = 0.04); in males, there was a high intake of beef (p = 0.04), milk drinks (p = 0.01), and beer (p = 0.05). This study provides further evidence for the hypothesis that dietary factors and alcohol consumption may play a role in the development of adenomatous colorectal polyps and that these factors are similar to dietary risk factors for colorectal cancer.

Aged↗

PubMed1989

India-US case-control study of age-related cataracts. India-US Case-Control Study Group.

In a hospital-based case-control study of 1441 patients with age-related cataracts and 549 controls, we studied associations between types of cataract--nuclear, cortical, posterior subcapsular, and mixed--and a number of physiologic, behavioral, environmental, and biochemical variables. Using polychotomous logistic regression analysis, we found an increased risk of cataract with lower educational achievement (all types of cataract), decreased cloud cover at place of residence (all types), use of aspirin less than once a month (posterior subcapsular and mixed), diets low in selected nutrients (posterior subcapsular, nuclear, and mixed), higher blood pressure (nuclear and mixed), lower body mass index (nuclear and mixed), use of cheaper cooking fuels (cortical, nuclear, and mixed), and lower levels of an antioxidant index based on red blood cell levels of glutathione peroxidase and glucose-6-phosphate dehydrogenase and plasma levels of ascorbic acid and vitamin E (posterior subcapsular and mixed). All risks cited were significantly different from those for the other cataract types, a finding that emphasizes the need to investigate the epidemiology of specific types of cataract.

Adult↗

PubMed1990

Occupation and risk for testicular cancer: a case-control study.

A case-control study of 271 testicular cancer cases aged 18-42, including 60 seminomas and 206 other germinal cell tumours, and 259 controls was carried out to study the association between occupation and testicular cancer risk. Study subjects were identified at three medical centres, two of which treat military personnel. Controls were men diagnosed with a cancer other than of the genital tract. Associations were identified between professional employment (administrators, teachers and other professionals) and risk for testicular seminoma, OR = 2.8 (95% Cl: 1.4-5.4) and between employment in production work and risk for other germinal cell tumours, OR = 1.8 (95% Cl: 1.1-2.7). No specific occupations within these broad groups were responsible for observed increases. Self-reported exposure to microwave and other radio waves was associated with an excess risk for both seminomas and other germinal cell tumours. However, an assessment of radio wave exposure based on job title did not support this finding. Although testicular cancer has been increasing in recent decades among young males, occupational factors did not appear to account for a substantial proportion of testicular cancer occurrence in the population studied.

Adolescent↗

PubMed1985

Lung cancer and use of cigarettes: a French case-control study.

A case-control study of 1,625 cases and 3,091 controls was conducted in France from 1976 to 1980 to compare the effects of different smoking habits, especially the use of filter cigarettes, tobacco types (light or dark), and the use of hand-rolled or manufactured cigarettes on the occurrence of lung cancer. All cases had histologically confirmed lung cancer; the controls were matched by sex, age, hospital of admission, and interviewer. The reported results concern only male nonsmokers and males who smoked (or had smoked) cigarettes exclusively, i.e., a total of 1,217 Kreyberg I and Kreyberg II cancer cases and 1,915 controls. Cigarette smoking was associated with both Kreyberg I and Kreyberg II cell categories although with different relative risks (RR) (17.2 and 3.6, resp.). Within the Kreyberg I category, RR were significantly increased (P less than .0001) with certain indices of duration and intensity of cigarette exposure, such as early age at first cigarette smoked, daily consumption, depth of inhalation, and duration of smoking. A significant difference in risk was found within the Kreyberg I category for nonfilter versus filter cigarette smokers (RR = 18.1 and 10.9, resp.) and dark versus light tobacco smokers (RR = 18.1 and 4.9, resp.) but not for hand-rolled versus manufactured cigarette smokers (RR = 19.8 and 16.0, resp.). When all the covariates were taken into account in a matched logistic regression, lung cancer risks for nonfilter versus filter cigarette smokers was RR = 1.23, for hand-rolled versus manufactured cigarette users RR = 1.22, and for dark versus light tobacco users RR = 1.94.

Adult↗

PubMed1992

Occupational risk factors for acute leukaemia: a case-control study.

A case-control study has been performed for occupational risk factors of acute leukaemia, based on 185 cases more than 30 years old and 513 matched controls. There was a significant excess of polyvalent farming and electronic engineers among professions of cases, and, in addition of metal workers when considering the professions pursued for more than 5 years. The corresponding exposures were analysed through a detailed questionnaire, and assessed by an industrial hygienist after blinding the case-control status. The odds ratios (OR) were computed after adjustment on matching variables and prior chemo- or radiotherapy treatment, and after stratification for the level and total duration of exposure. There was no excess of professional exposure to ionizing radiation among cases. A significant relationship was observed between acute leukaemia and high or medium exposure to benzene, as well as over 10 years high or medium exposure to exhaust gas. In addition a significant relationship was observed with exposure to pesticides--insecticides and/or weed killers--and to electric and magnetic fields (EMF). The relationship with pesticides was significant when considering high or medium exposure to weed killers and more than 10 years exposure to both subtypes of pesticides. The relationship with pesticides and EMF remained significant when confounding factors were taken into consideration and after adjustment on co-exposure to benzene. The cytological studies showed that acute leukaemias following exposure to benzene (high or medium) and to EMF were only of myelogenous subtypes, whereas those following exposure to pesticides were divided between lymphoblastic and myeloblastic subtypes. Cytogenetic studies failed to show increased frequency of chromosomal abnormalities, as described in acute leukaemias secondary to anti-cancer treatments. Our study adds credence to the hypothesis that pesticides and EMF are leukaemogenic agents, together with benzene.

Acute Disease↗