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W J Blot

Publications and source records attributed to W J Blot.

At least 19 recordsLinked to original sources
PubMed2006

Parkinson's disease and other basal ganglia or movement disorders in a large nationwide cohort of Swedish welders.

INTRODUCTION: Although it has been hypothesised that metal welding and flame cutting are associated with an increased risk for Parkinson's disease due to manganese released in the welding fume, few rigorous cohort studies have evaluated this risk. METHODS: The authors examined the relation between employment as a welder and all basal ganglia and movement disorders (ICD-10, G20-26) in Sweden using nationwide and population based registers. All men recorded as welders or flame cutters (n = 49,488) in the 1960 or 1970 Swedish National Census were identified and their rates of specific basal ganglia and movement disorders between 1964 and 2003 were compared with those in an age and geographical area matched general population comparison cohort of gainfully employed men (n = 489,572). RESULTS: The overall rate for basal ganglia and movement disorders combined was similar for the welders and flame cutters compared with the general population (adjusted rate ratio (aRR) = 0.91 (95% CI 0.81 to 1.01). Similarly, the rate ratio for PD was 0.89 (95% CI 0.79 to 0.99). Adjusted rate ratios for other individual basal ganglia and movement disorders were also not significantly increased or decreased. Further analyses of Parkinson's disease by attained age, time period of follow up, geographical area of residency, and educational level revealed no significant differences between the welders and the general population. Rates for Parkinson's disease among welders in shipyards, where exposures to welding fumes are higher, were also similar to the general population (aRR = 0.95; 95% CI 0.70 to 1.28). CONCLUSION: This nationwide record linkage study offers no support for a relation between welding and Parkinson's disease or any other specific basal ganglia and movement disorders.

Adult↗
PubMed2005

Use of antibiotics and risk of breast cancer: a population-based case-control study.

We examined the use of antibiotics among 2728 women with a first diagnosis of breast cancer during 1994-2003, and 27 280 population controls in North Jutland County, Denmark, based on hospital discharge diagnoses, prescription use from 1989 to 2002, and population registry data. We found no increased relative risk of breast cancer associated with use compared with nonuse. The odds ratio for breast cancer associated with more than 10 prescriptions for antibiotics was 1.00 (95% CI 0.86 -1.15). Relative risks were similar for different classes of antibiotics. A subanalysis based on cases and controls younger than 70 years of age, with data on first birth and number of children, showed similar risk estimates even after adjustment for age at first birth and parity. In our study, use of antibiotics was not associated with an increased risk of breast cancer.

Aged↗
PubMed2003

Risk of cancer in a large cohort of nonaspirin NSAID users: a population-based study.

There is increasing evidence of an inverse association between use of nonsteroidal anti-inflammatory drugs (NSAIDs) and risk of colorectal cancer. However, data regarding other cancer sites are limited. Using data from the population-based North Jutland Prescription Database and the Danish Cancer Registry, we compared cancer incidence among 172 057 individuals prescribed nonaspirin NSAIDs with expected incidence (based on county-specific cancer rates) during a 9-year study period. A total of 6081 incident cancer cases were diagnosed among NSAID users vs 5722 expected (standardised incidence ratio (SIR) 1.1, 95% confidence interval (CI)1.0-1.1). The SIRs for colon and rectal cancer among persons who obtained 10 or more prescriptions were 0.7 (95% CI 0.6-0.9) and 0.6 (95% CI 0.4-0.9), respectively. Similarly, reduced risk estimates were found for stomach (SIR 0.7, 95% CI 0.4-1.1) and ovarian cancer (SIR 0.7, 95% CI 0.4-1.0). Standardised incidence ratios for other cancers among those with 10 or more prescriptions tended to be close to 1.0, except for lung, kidney, and prostate cancers with SIRs of 1.3 (95% CI 1.1-1.6), 1.4 (95% CI 0.9-2.1), and 1.6 (95% CI 1.3-2.0), respectively. We found protective associations of NSAIDs against colon, rectal, stomach, and ovarian cancer. Reasons for the increased risk for some cancer sites are not clear.

Aged↗
PubMed2003

A population-based cohort study of the risk of colorectal and other cancers among users of low-dose aspirin.

Using data from the population-based Prescription Database of North Jutland County and the Danish Cancer Registry, we compared cancer incidence among 29 470 individuals prescribed low-dose aspirin at maximum doses of 150 mg with expected incidence based on county-specific cancer rates, during a 9-year study period. We observed 2381 cancer cases compared with 2187 expected, yielding a standardised incidence ratio (SIR) of 1.09 (95% confidence interval (CI), 1.05-1.13). No apparent risk reductions were found for cancers of the colon (SIR, 0.9; 95% CI, 0.7-1.1) or rectum (SIR, 1.0; 95% CI, 0.8-1.2), or for other site-specific cancers. Increased SIRs were observed for kidney cancer (SIR, 1.4; 95% CI, 1.1-1.7) and brain cancer (SIR, 1.7; 95% CI, 1.3-2.2), although the excess in the latter was confined to the first year of follow-up. Stratification by number of prescriptions and duration of follow-up revealed no apparent trends. The SIR for colorectal cancer was close to unity (SIR, 0.9; 95% CI, 0.6-1.2) among persons with 10 or more prescriptions who were followed for at least 5 years. Our results do not support a major protective effect of low-dose aspirin on the development of colorectal or other cancers. The observed excesses of kidney and brain cancers are not likely to be causally related to the use of low-dose aspirin.

Aged↗
PubMed2003

Development of a culturally sensitive food frequency questionnaire for use in the Southern Community Cohort Study.

A food frequency questionnaire (FFQ) was developed to assess long-term habitual dietary intake in a cohort of approximately 100,000 40 to 79 year-old men and women living in the Southeastern US. Using the NHANES-III database for the southem region for specific race and sex subgroups, a list of 262 food categories was developed, coded and reduced to 102 food items that could discriminate between racial groups and account for large portions of cancer-relevant nutrients. The developed FFQ was tested in a pilot study in three southeastern states involving 239 African Americans and Whites, aged 56.9 +/- 12.2 years. The frequencies of consumption and portion sizes of the 102 foods were determined and intakes of various nutrients were estimated and compared with the NHANES-III data. African Americans reported higher total energy intakes and higher consumption of macronutrients and several micronutrients, compared to Whites. Estimated nutrient indices were higher among pilot study than among NHANES-III participants, although adjustment for total energy essentially eliminated the differences. Analysis of the frequency distribution of individual foods shows that the questionnaire includes commonly eaten foods that can discriminate between African Americans and Whites. The FFQ is currently being calibrated within the cohort study population.

Adult↗
PubMed2001

Acetaminophen, aspirin, and chronic renal failure.

BACKGROUND: Several epidemiologic studies have demonstrated an association between heavy consumption of nonnarcotic analgesics and the occurrence of chronic renal failure, but it is unclear which is the cause and which is the effect METHODS: In a nationwide, population-based, case-control study of early-stage chronic renal failure in Sweden, face-to-face interviews were conducted with 926 patients with newly diagnosed renal failure and 998 control subjects, of whom 918 and 980, respectively, had complete data. We used logistic-regression models to estimate the relative risks of disease-specific types of chronic renal failure associated with the use of various analgesics RESULTS: Aspirin and acetaminophen were used regularly by 37 percent and 25 percent, respectively, of the patients with renal failure and by 19 percent and 12 percent, respectively, of the controls. Regular use of either drug in the absence of the other was associated with an increase by a factor of 2.5 in the risk of chronic renal failure from any cause. The relative risks rose with increasing cumulative lifetime doses, rose more consistently with acetaminophen use than with aspirin use, and were increased for most disease-specific types of chronic renal failure. When we disregarded the recent use of analgesics, which could have occurred in response to antecedents of renal disease, the associations were only slightly attenuated CONCLUSIONS: Our results are consistent with the existence of exacerbating effects of acetaminophen and aspirin on chronic renal failure. However, we cannot rule out the possibility of bias due to the triggering of analgesic consumption by predisposing conditions.

Acetaminophen↗
PubMed2001

Angiotensin-converting enzyme inhibitors and the risk of cancer: a population-based cohort study in Denmark.

BACKGROUND: A recent observational study suggested that the use of angiotensin-converting enzyme (ACE) inhibitors protects against cancer in general and against breast and female reproductive tract cancers in particular. To explore these hypotheses, the authors examined cancer risk among users of ACE inhibitors in North Jutland County, Denmark. METHODS: Using data from the population-based Prescription Database of North Jutland County and the Danish Cancer Registry, cancer incidence among 17,897 individuals prescribed ACE inhibitors was compared with expected incidence based on county specific cancer rates during an 8-year study period with a mean follow-up of 3.7 years. Standardized incidence ratios (SIRs) with corresponding 95% confidence intervals (95% CIs) were calculated for cancers overall and at selected sites. In addition, the authors performed a direct comparison of users of ACE inhibitors with users of beta-blockers or calcium channel blockers (n = 47,579 individuals) by means of a Cox proportional hazards model. RESULTS: Overall, 909 cancer cases were observed among users of ACE inhibitors, with 846 expected based on general population rates, yielding an SIR of 1.07 (95% CI, 1.01-1.15). No risk reductions were observed for cancers of the breast and female reproductive tract, whereas nonsignificantly decreased SIRs were observed for cancers of the esophagus, stomach, and liver. Cancer of the kidney was found in significant excess (SIR, 1.6; 95% CI, 1.1-2.2). Stratification by duration of follow-up or number of prescriptions revealed no apparent trends, except for a tendency toward decreasing risk with increasing length of follow-up for smoking-related cancers. The direct comparison of users of ACE inhibitors with users of beta-blockers or calcium channel blockers yielded results comparable to those derived from the comparison with the general population, with a hazard ratio for cancer overall of 1.01 (95% CI, 0.93-1.09). CONCLUSIONS: This large, population-based cohort study did not confirm a protective effect of ACE inhibitors on the development of cancer. The excess of kidney cancer observed likely reflects a correlation between hypertension and kidney cancer. Further investigation is needed to evaluate the long-term effects of ACE inhibitors beyond the observation period of this and previous studies. Also, the suggestive evidence of decreased risks for upper digestive system cancers and for smoking-related cancers over time may warrant additional investigation.

Adult↗
PubMed2001

Nationwide study of cancer risk among hip replacement patients in Sweden.

BACKGROUND: Orthopedic implants and their fixatives contain materials with carcinogenic potential. Whether these implants are linked to subsequent cancer development remains unknown, mainly because large-scale, long-term follow-up data are scarce. METHODS: We conducted a nationwide cohort study in Sweden to examine cancer incidence among 116,727 patients who underwent hip replacement surgery during the period from 1965 through 1994. Through record linkage to the Swedish Cancer Register, we identified all incident cancers through 1995 in this population (693,954 person-years of observation). For each cancer type, the observed number of cases was divided by that expected in the general Swedish population to produce standardized incidence ratios (SIRs). RESULTS: Relative to the general population, the cohort had no overall cancer excess (SIR = 1.01; 95% confidence interval [CI] = 0.99 to 1.03). However, we observed elevated SIRs for prostate cancer (SIR = 1.16; 95% CI = 1.11 to 1.22) and melanoma (SIR = 1.15; 95% CI = 1.01 to 1.30) and a reduction in stomach cancer risk (SIR = 0.83; 95% CI = 0.75 to 0.92). Long-term follow-up (>or=15 years) revealed an excess of multiple myeloma (SIR = 1.86; 95% CI = 1.01 to 3.11) and a statistically nonsignificant increase in bladder cancer (SIR = 1.42; 95% CI = 0.98 to 1.99). There was no material increase in risk for bone or connective tissue cancer for either men or women in any follow-up period. CONCLUSIONS: In this, the largest study to date, hip implant patients had similar rates of most types of cancer to those in the general population. Although the excesses of melanoma, multiple myeloma, and prostate and bladder cancers may be due to chance, confounding, or detection bias and should be interpreted cautiously, they warrant further investigation because of the ever-increasing use of hip implants at younger ages.

Aged↗
PubMed2001

Family history of cancer and risk of esophageal and gastric cancers in the United States.

The worldwide rates for histology- and subsite-specific types of esophageal and gastric cancer reveal strikingly divergent patterns. The contribution of environmental and genetic factors has been explored in several high-incidence areas, but data on genetic influences are scarce for Western countries. Using data from a multicenter, population-based, case-control study on 1,143 cases and 695 controls in the United States, we evaluated whether a family history of digestive or other cancers was associated with an increased risk of esophageal adenocarcinoma (n = 293), esophageal squamous cell carcinoma (n = 221), gastric cardia adenocarcinoma (n = 261) or non-cardia gastric adenocarcinoma (n = 368). After adjusting for other risk factors, individuals reporting a family history of digestive cancers experienced no increased risk of either type of esophageal cancer but they were prone to adenocarcinomas of the gastric cardia [odds ratio (OR) = 1.34, 95% confidence interval (CI) 0.91-1.97] and non-cardia segments (OR =1.46, 95% CI 1.03-2.08). This familial tendency, particularly for non-cardia gastric tumors, was largely explained by an association with family history of stomach cancer (OR = 2.52, 95% CI 1.50-4.23). In addition, family history of breast cancer was associated with increased risks of esophageal adenocarcinoma (OR = 1.74, 95% CI 1.07-2.83) and non-cardia gastric adenocarcinoma (OR = 1.76, 95% CI 1.09-2.82). Also seen were non-significant familial associations of esophageal squamous-cell cancer with prostate cancer as well as non-cardia gastric cancer with leukemia and brain tumors, though these relationships must be interpreted with caution. Our data point to the role of familial susceptibility to gastric cancer, but not to any form of esophageal cancer, in the United States.

Adenocarcinoma↗
PubMed2001

Connective tissue disease and other rheumatic conditions following cosmetic breast implantation in Denmark.

OBJECTIVE: To examine the occurrence of connective tissue diseases (CTDs) as well as ill-defined and other rheumatic conditions among Danish women with cosmetic silicone breast implants. PATIENTS AND METHODS: A total of 2761 women with breast implants and 8807 control subjects were identified from plastic surgery private clinics and from public hospital plastic surgery departments. Women operated on at plastic surgery private clinics were identified through the files of each clinic, while women operated on at public hospitals were identified using the nationwide Danish National Registry of Patients. The control group consisted of women who underwent cosmetic surgery other than breast implantation or who only had a consultation. All women were followed up from January 1, 1977, through December 31, 1996, through the Danish National Registry of Patients for the occurrence of CTD as well as ill-defined and other rheumatic conditions. For the study period January 1, 1977, through December 31, 1994, the Danish National Registry of Patients contains information on hospitalization only, whereas data on outpatient visits are included from 1995 on, thus improving the sensitivity of the data. The implant and control groups were compared with the Danish population rates for CTD and ill-defined and other rheumatic conditions, and a direct comparison between the implant and control groups was also performed. RESULTS: When compared with rates from the general population, no excess of definite CTD was observed in the implant cohorts. For ill-defined and other rheumatic conditions, statistically significant excesses of unspecified rheumatism were observed in both the implant and control cohorts when compared with national rates. A direct comparison between the implant and control cohorts found no material differences between the groups. CONCLUSIONS: The findings of this study support previous investigations and independent review panel conclusions that an association between silicone breast implants and definite CTDs is unlikely. The observation of an excess of unspecified rheumatism among women with implants and among control women suggests that women undergoing cosmetic plastic surgery have hospitalization rates for this condition in excess of those from the general population.

Adolescent↗
PubMed2001

Urinary concentrations of trichloroacetic acid in Danish workers exposed to trichloroethylene, 1947-1985.

BACKGROUND: Since 1947, the National Labour Inspection Service in Denmark has relied upon urinary measurements of trichloroacetic acid (TCA) in surveys of the occupational exposure to trichloroethylene (TCE). METHODS: We examined the paper files relating to 2397 TCA measurements to extract information about the year, the company, the work process and the worker. We used multiple regression models to analyze the effects of various factors on the urinary concentration of TCA. RESULTS: The regression analyses showed that (1) a four-fold decrease in TCA concentrations occurred from 1947 to 1985; (2) the highest concentrations were observed in the iron and metal, chemical, and dry cleaning industries; (3) TCA levels were two times higher among men compared with women in the iron and metal and dry cleaning industries; (4) TCA concentrations were higher among younger compared with older workers; and (5) persons working in an area in which TCE was used, but not working with TCE themselves, also showed urinary TCA levels indicative of exposure. CONCLUSIONS: Calendar year, type of industry, degree of contact with TCE, sex and age were predictors of TCA concentration in the urine of Danish workers.

Denmark↗
PubMed2001

Risk of hospitalization resulting from upper gastrointestinal bleeding among patients taking corticosteroids: a register-based cohort study.

PURPOSE: We assessed the risk of hospitalization for upper gastrointestinal bleeding among patients using systemic corticosteroids, accounting for the use of other drugs that may increase the risk of bleeding. SUBJECTS AND METHODS: We conducted a population-based cohort study in North Jutland County, Denmark. Data on the use of corticosteroids, nonsteroidal anti-inflammatory drugs, aspirin, and anticoagulants during 1991 to 1995 were obtained from a countywide prescription database. All hospitalizations because of upper gastrointestinal bleeding were identified through the Hospital Discharge Registry. The observed numbers of patients with gastrointestinal bleeding in various exposure categories among corticosteroid users were compared with the expected number based on the North Jutland population who did not receive prescriptions for any of the drugs under study. RESULTS: A total of 45,980 patients accrued 18,379 person-years of corticosteroid use. There were 109 hospital admissions for gastrointestinal bleeding among corticosteroid users, compared with 26 expected, yielding a relative risk of 4.2 [95% confidence interval (CI): 3.4 to 5.0]. Among corticosteroid users who did not use other drugs associated with gastrointestinal bleeding, the relative risk was 2.9 (95% CI: 2.2 to 3.7). The relative risk decreased further to 1.9 (95% CI: 1.4 to 2.5) when current corticosteroid usage was compared with former usage. CONCLUSION: We observed an increased risk of hospitalization because of upper gastrointestinal bleeding among patients prescribed corticosteroids, especially among those who use other medications. Confounding from the underlying disease may also have contributed to the observed increase in risk.

Adolescent↗
PubMed2001

Caffeine metabolism and the risk of spontaneous abortion of normal karyotype fetuses.

OBJECTIVE: To investigate whether the rate of caffeine metabolism influences spontaneous abortion risk. METHODS: We studied 101 women with normal karyotype spontaneous abortions and 953 pregnant women at 6-12 gestational weeks. Participants reported on caffeine intake and provided urine for phenotyping cytochrome P4501A2 (CYP1A2) activity and blood for genotyping N-acetylation (NAT2) status. We calculated odds ratios (OR) and 95% confidence intervals (CI) to evaluate the association between each of the two metabolic indices and spontaneous abortion risk and also the potential interaction between caffeine intake and metabolic activity on such risk. In calculating the associations between the metabolic indices and risk of spontaneous abortion, we had 80% power to detect an OR of 2.1, with a Type I error of 0.05. RESULTS: Slow acetylators had a nonsignificantly increased risk for spontaneous abortion (OR 1.36, 95% CI 0.84, 2.21) and recurrent spontaneous abortion (OR 2.51, 95% CI 0.81, 7.76). In contrast, low CYP1A2 activity was associated with a significantly decreased risk for spontaneous abortion (OR 0.35, 95% CI 0.20, 0.63). Caffeine was a risk factor for spontaneous abortion among women with high, but not low, CYP1A2 activity (OR 2.42, 95% CI 1.01, 5.80 for 100-299 mg/day; OR 3.17, 95% CI 1.22, 8.22 for 300 mg/day or more, among women with high CYP1A2 activity). CONCLUSION: The findings indicate that high CYP1A2 activity may increase the risk of spontaneous abortion, independently or by modifying the effect of caffeine. The results regarding NAT2 are less conclusive but suggest that slow acetylators may be at elevated risk of spontaneous abortion.

Abortion, Spontaneous↗
PubMed2001

Neurological disease among women with silicone breast implants in Denmark.

OBJECTIVES: To investigate the risk of neurological disease among women with cosmetic breast implants. MATERIAL AND METHODS: We identified 1,653 women who had undergone breast implant surgery at private clinics in Denmark and a comparison cohort of 1,736 women who underwent other types of cosmetic surgery at the same clinics. Ratios of observed-to-expected numbers of hospitalizations for neurological disease in the private implant and comparison cohorts were calculated, separately and combined with data from updated public hospital cohorts. RESULTS: The occurrence of neurological disease in the private clinic implant cohort was comparable to that in the general population. A similar risk pattern was observed in the private clinic comparison cohort. When data for these private clinic cohorts were combined with updated data for public hospital cohorts, excess risks for neurological disorders were seen in both implant and comparison cohorts, reaching statistical significance only in the comparison cohort. CONCLUSION: Our findings indicate no causal association between silicone breast implants and neurological disease.

Adult↗
PubMed2001

Outlet strut fracture of Björk-Shiley convexo-concave valves: can valve-manufacturing characteristics explain the risk?

BACKGROUND: Björk-Shiley 60 degrees convexo-concave prosthetic heart valves (Shiley, Inc, Irvine, Calif, a subsidiary of Pfizer, Inc) continue to be a concern for approximately 35,000 nonexplanted patients worldwide, with approximately 600 events reported to the manufacturer to date. Fractures of the outlet struts of the valves began to appear in the early 1980s and have continued to the present, but their causes are only partially understood. METHODS: A matched case-control study was conducted evaluating manufacturing records for 52 valves with outlet strut fractures and 248 control subjects matched for age at implantation, valve size, and valve position. RESULTS: In addition to the risk factors recognized as determinants of outlet strut fracture, the United Kingdom case-control study has observed 7- to 9-fold increased risk with performance of multiple hook deflection tests. This test was performed more than once, usually after rework on the valve. Six valves in this study underwent multiple hook deflection tests, of which 4 experienced an outlet strut fracture. Cracks and further rework were noted for these valves. Significant associations were also observed between outlet strut fracture and disc-to-strut gap measurements taken before the attachment of the sewing ring. CONCLUSIONS: It is our view that a combination of factors related to valve design, manufacturing process, and patient characteristics are responsible for outlet strut fractures of Björk-Shiley convexo-concave valves. Multiple hook deflection tests have emerged as a potential new risk factor for outlet strut fracture in both The Netherlands and the United Kingdom. This factor appears to be correlated with the presence of other abnormalities. A further study is needed to investigate the factors correlated with multiple hook deflection tests. On confirmation of risk, the presence of multiple hook deflection tests may be added to equations, quantifying the risk of outlet strut fracture for comparison against risk of mortality and serious morbidity from explant operations.

Analysis of Variance↗
PubMed2001

Connective tissue disease after hip and knee implant surgery.

OBJECTIVE: To increase the knowledge of the long-term effects of artificial hip and knee joint implants. METHODS: The study groups consisted of 24,636 patients with osteoarthritis who underwent hip implant surgery and 5,221 who received knee implants during 1977-89. The post-implant rate of hospitalization for connective tissue disease (CTD) was compared with the rate in the general population of Denmark and with that among osteoarthritis patients without implant surgery. RESULTS: The rates of hospitalization for CTD were higher than the background level among both hip and knee implant patients with osteoarthritis, whereas the comparison with non-implanted osteoarthritis patients revealed that the hospitalization rate for CTD was reduced after hip implant surgery, but increased after knee implant surgery. CONCLUSION: Since the materials used in hip and knee implants in Denmark are not substantially different, these results are unlikely to reflect an implant effect but rather the selection criteria of referral for implant surgery.

Aged↗
PubMed2001

Comparison of surrogate with self-respondents regarding medical history and prior medication use.

BACKGROUND: The self-report of medical history and medication use is a common feature of epidemiological research. METHODS: In a unique re-interview study, we evaluated the concordance of medical conditions and past medication use reported in two similar interviews 5 years apart. RESULTS: In 196 re-interviews with the subjects themselves, and in 107 with next-of-kin of subjects who died after the first interview, agreement was good or excellent (kappa > or =0.40) for 90% (9/10) of the conditions asked about in the personal medical history for both next-of-kin and self-respondents. Agreement was excellent (kappa >0.75) for two conditions, high blood pressure and hysterectomy, among self-respondents. Self- and surrogate respondents also showed similar reproducibility for prescription medications, but next-of-kin respondents tended to have poor agreement (kappa <0.40) for over-the-counter (OTC) medications such as antacids, antihistamines, and analgesics. Next-of-kin also less reliably reported a family history of cancer. When analyses were stratified by type of surrogate respondent, concordance between the two interviews was generally higher for spouses than for other surrogate respondents. CONCLUSIONS: This research demonstrates that personal medical history and prescription medication use may be as reliably reported by next-of-kin as self-respondents, but suggests that additional information may be needed to validate measures of OTC medication use and family history of cancer for next-of-kin respondents, possibly through the review of hospital records.

Adult↗