Search

The article presents questions and answers related to the study of infection risks after splenectomy including the patients who were studied, the methodology of the study, and the findings of the researchers.

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.

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.

From the 1950s to the 1980s, hexavalent chromium compounds were used as additives at certain water-cooling towers at three southern California gas compressor facilities. Claims of potential residential chromium exposure prompted the examination of age-adjusted mortality rates during 1989 to 1998 for lung cancer, all cancer, and all deaths for neighborhoods near versus distant from the plants. Differences in the rates between areas tended to be small and not statistically significant. The only significant difference was a lower, rather than higher, rate of total cancer among women in the potentially exposed areas. Study limitations preclude a definitive assessment of risk, but similar to previous investigations of cancer in relation to environmental chromium exposure in other locations, this study found no evidence of a cancer hazard among residents living near these California gas compressor facilities.

Background: Pancreatic cancer is the fifth leading cause of cancer-related mortality in the United STATES: Although smoking and age are known risk factors for pancreatic cancer, several case reports and case-control studies have suggested that there is also a familial risk. We evaluated whether a family history of pancreatic cancer increases the risk of pancreatic cancer in first-degree relatives and whether smoking and younger age at cancer diagnosis further increase this risk., Methods: We conducted in-person interviews with 247 patients ("case probands") with pancreatic cancer and 420 population-based control probands to collect risk factor data and pancreatic cancer family history for 1816 first-degree relatives of the case probands and 3157 first-degree relatives of the control probands. We analyzed the data by unconditional logistic regression models, with adjustment for correlated data by use of generalized estimating equations. All statistical tests were two-sided., Results: A positive family history of pancreatic cancer (i.e., being related to a case proband) or ever-smoking cigarettes approximately doubled the risk of pancreatic cancer (relative risk [RR] = 2.49; 95% confidence interval [CI] = 1.32 to 4.69; RR = 2.04; 95% CI = 1.09 to 3.83, respectively). The RR increased to 8.23 (95% CI = 2.18 to 31.07) for relatives who ever smoked and were related to a case proband who was diagnosed before age 60 years., Conclusion: Routine questioning of patients about a family history of pancreatic cancer, the age of onset of this cancer in their relatives, and the patient's smoking status may identify individuals at high risk of pancreatic cancer. Future research exploring the genetic and environmental interactions associated with the risk of pancreatic cancer is critically important.

Case reports have suggested that children born to women with silicone breast implants may have an excess risk of rheumatic disease and/or esophageal disorders. In Sweden, the authors conducted a retrospective cohort study of 5,874 children born to women with cosmetic breast implants and 13,274 children born to women who had breast reduction surgery. Using national registers, they computed hospitalization rates for rheumatic and esophageal disorders, incidence rates for cancer, and prevalence rates for congenital malformations and perinatal death. Relative to children of women who had breast reduction surgery, children born to women who had cosmetic breast implants were not at excess risk of rheumatic disease (relative risk [RR] = 1.1; 95% confidence interval [95% CI], 0.2-5.3), esophageal disorders (RR = 1.0; 95% CI, 0.7-1.6), cancer (RR = 0.3; 95% CI, 0.0-2.5), congenital malformations in total (RR = 1.0; 95% CI, 0.6-1.5), or specifically involving the digestive organs (RR = 0.5; 95% CI, 0.2-1.3) or perinatal death (RR = 0.9; 95% CI, 0.5-1.8). The rates of these health outcomes among children born after a mother's implant surgery were also not significantly higher than among children born before a mother's implant surgery. This study provides no evidence that certain hypothesized health outcomes are more likely among the children of women with cosmetic breast implants.

Background and Aim of the Study: Approximately 82,000 Björk-Shiley convexo-concave (BSCC) 60 degree prosthetic heart valves were implanted in patients worldwide between 1979 and 1986. Outlet strut fractures (OSF) of some of the valves were first reported shortly after their introduction. Here, the determinants of OSF are examined, and the between-country variation and long-term risk are assessed., Methods: Cohorts of patients in the UK, Netherlands and USA with 15,770 BSCC 60 degree heart valves were followed up to 18 years for the occurrence of OSF., Results: Crude rates of OSF were highest in the UK (0.18% per year), intermediate in the Netherlands (0.13%), and lowest in the USA (0.06%), although risk factor adjustment reduced the inter-country differences. Furthermore, in the UK and Netherlands, OSF rates (particularly for mitral valves) declined with time since implantation, and between-country differences were considerably diminished 10 or more years post implantation. The risk of OSF decreased steadily with advancing patient age. Fracture rates were lower among women than men, and also varied significantly with valve size and position and OSF status of other valves in the same shoporder., Conclusion: This long-term follow up of BSCC 60 degree heart valve patients indicates that risk factors for valve fracture are generally similar in the UK, Netherlands and USA. It also identifies a strong association between fracture risk and age, newly reveals gender-related differences, and shows that the risk of valve fracture persisted, albeit at a reduced rate, into the 1990s.

A retrospective cohort study was performed in Sweden to evaluate the possibility that an individual symptom or constellation of illness symptoms related to silicone occurs in women after breast implant surgery. A random sample (n = 2500) of all women in the Swedish national implant registry who underwent breast augmentation surgery with alloplastic breast implants during the years 1965 through 1993 was compared with a sample (n = 3500) of women who underwent breast reduction surgery during the same period, frequency matched to the implant patients for age and calendar year at the time of surgery. In total, 65 percent of the breast implant patients (n = 1546) and 72 percent of the breast reduction patients (n = 2496) completed a self-administered questionnaire covering 28 rheumatologic and other symptoms and lifestyle and demographic factors. Practically all of the 28 symptoms inquired about were reported more often by women in the breast implant cohort, with 16 (57 percent) significantly more common in breast implant recipients. In contrast, few significant differences or consistent patterns were observed in the length of time since the implant and in the type (silicone or saline) or volume of the implant. Although women with breast implants report a multitude of symptoms more often than women who have breast reduction surgery, the lack of specificity and absence of dose-response relationships suggest that the excess of reported symptoms is not causally related to cosmetic implants.

Epidemiologic studies have found no association between breast implants and cancer or well-defined connective tissue diseases. However, women with cosmetic breast implants continue to report specific as well as nonspecific physical and psychological symptoms after receiving their implants. In an attempt to determine whether local complications of implantation may contribute to this excess of symptom reporting, the authors studied a large cohort of women in Sweden with cosmetic breast implants (n = 1280) and a comparison cohort of women who had cosmetic breast reduction surgery (n = 2211). Both groups of women had operations between 1969 and 1996. Medical record reviews of local complications revealed that approximately 31 percent of the women with cosmetic breast implants had an implant change, implant leakage, or a capsulotomy. Capsulotomies occurred more often in women who were age 35 or older at the time of the operation, had ever smoked, and had implants with a smooth surface. On self-administered questionnaires, symptoms were reported more often by the women who had implants regardless of whether they had local complications. Twenty of the 28 symptoms occurred more frequently among women with local complications and breast implants, compared with the women in the breast reduction comparison group or the women with breast implants but no local complications. This study suggests that local complications, particularly capsular contractures as indicated by capsulotomy, may be an important factor to consider when studying symptom reporting among women with breast implants.

To determine whether women with cosmetic breast implants have distinct demographic, lifestyle, and reproductive characteristics that put them at increased risk for subsequent morbidity, the authors compared 1,369 such women to 2,211 women who had undergone breast reduction surgery, and to a random sample of 49,262 women from the general population of Sweden. Information was collected through self-administered questionnaires, and comparisons were made using the prevalence odds ratio. Women with cosmetic breast implants were significantly (p <0.05) more likely to be current smokers, have a lower body mass index, have had a prematurely terminated pregnancy (induced abortion or miscarriage), and have had fewer live births than either women who underwent breast reduction or women from the general population. Type of implant (silicone gel or saline) did not modify the associations. Regardless of the comparison group used, studies of the health effects of breast implants need to consider that women who undergo cosmetic breast implantation have certain distinct characteristics.

Methods were developed to assess exposure to a wide variety of chemicals for nearly 80,000 workers involved in manufacturing aircraft since 1928. The facilities, now closed, consisted of four major plants, over 200 buildings, and a changing workforce during 60 years of operation. To access chemical exposures by specific jobs and calendar years, we reviewed complete work histories, examined detailed job descriptions available going back to 1940, interviewed long-term employees, conducted walk-through visits of aircraft manufacturing plants, reviewed comprehensive environmental assessment reports and industrial hygiene surveys on the facilities, and built on experience gained in previous studies of the aircraft industry. Using computer-based imaging systems, we examined and evaluated the complete work histories found on service record cards for the cohort and abstracted detailed information on all jobs held among the factory workers who had been employed for at least one year. Jobs were classified into one of three exposure categories related to the use of specific chemicals: routine, intermittent, and none, and these classifications were subsequently used in the epidemiological analyses. The approach to exposure assessment began with the most general categorization of employees (i.e., all workers) and then became progressively more specific, that is, factor workers, job families (similar activities), job titles, and jobs with chemical usage (exposure potential). Because exposure surveys were limited or absent during the early years of plant operations, we did not assign quantitative measures of exposure to individual job activities. Instead, we used as our exposure metric, the length of time spent in jobs with potential exposure to the chemical. Important occupational exposures included chromate-containing compounds such as used in paint primers, trichloroethylene and perchloroethylene used as vapor-state degreasing solvents, and a broad range of other solvents.

Objective: To determine if finger and hand joint prostheses or temporomandibular joint (TMJ) implants may be involved in the initiation of specific connective tissue diseases (CTD), a nationwide cohort in Denmark was followed prospectively to evaluate rates of CTD after receiving these implants., Methods: Danish patients with finger and hand joint implants (n = 562) or TMJ implants (n = 351) were identified and followed for subsequent hospitalizations. Observed numbers of hospitalizations due to CTD were compared with expected numbers based on national CTD hospitalization rates. To avoid confounding by indication, patients with a hospital discharge diagnosis of a CTD prior to prosthetic surgery were excluded from the cohort., Results: After 4142 person-years of followup in the finger and hand joint cohort, 9 hospitalizations due to CTD were found [standard hospitalization rate (SHR) = 1.5; 95% CI 0.7-2.9]. The TMJ cohort had 1500 person-years of followup and 2 hospitalizations due to CTD (SHR = 1.3; 95% CI 0.2-4.5)., Conclusion: This is the first cohort study to examine the relations between these implants and CTD. Although the number of events was small, this systematic national study revealed no significant or large increase in risk of CTD after finger and hand joint implants or TMJ implants.

Accurate assessment of occupational history is critical in case-control studies of disease risk associated with employment. However, in some studies of rapidly fatal diseases, a surrogate or next of kin is interviewed rather than the study subject. In a unique re-interview study of subjects from a community-based case-control study originally interviewed 5 years earlier, we evaluated the level of agreement between (1) subjects and their surrogates on re-interview among those who had died since the first interview, and (2) subjects themselves and their responses at re-interview among those still living (to use as a comparison) regarding work history and specific occupational exposures. For employment start and stop dates, number of years worked, and number of jobs reported in the 1980 interview, exact agreement was poor for surrogate respondents and for self-respondents in the re-interview, with percentages ranging from 4% to 40%. Agreement was similar for surrogates and self-respondents for job and industry worked the longest, but percent of agreement among surrogates was significantly lower than among the self-respondents for job and industry worked last. Five (28%) of the kappa values for the industry in which the subject worked had high agreement (kappa > 0.75) for self-respondents and surrogates. None of the kappa statistics for materials handled by subjects in their jobs had high agreement, and 57% of the kappa statistics had poor agreement (kappa 0.0 to 0.39). This study suggests that occupational histories obtained by interview are poorly reproduced, and existing methods may need improvement to collect reliable occupational data. Further, the findings indicate that caution should be exercised when creating a job-exposure matrix based on such data.

An earlier cohort study tracked the mortality experience through 1988 of male employees at five utility companies in the United States. Workers employed by the Pacific Gas and Electric Company (PG&E) were part of that study, but results for PG&E employees overall or for those involved in gas generator plant operations where hexavalent chromium compounds were used in open and closed systems from the 1950s to early 1980s were not reported. To evaluate risk of lung cancer and other diseases, a cohort of 51,899 PG&E male workers was followed for mortality from 1971 through 1997. Observed numbers of deaths were compared with those expected based on rates in the general California population, with standardized mortality ratios (SMR) and corresponding 95% confidence intervals (CI) calculated for the total cohort and for subsets defined by potential for gas generator plant exposure. A total of 10,591 deaths were observed, a number significantly less than expected (SMR, 0.89; 95% CI, 0.87 to 0.91). No significant excesses of total or specific cancers were observed, with SMR typically near or below 1.0. Lung cancer mortality in the entire cohort was close to expected (SMR, 0.98; 95% CI, 0.92 to 1.05), with no excess detected among persons who worked (SMR, 0.81; 95% CI, 0.35 to 1.60) or trained (SMR, 0.57; 95% CI, 0.12 to 1.67) at gas generator facilities. Furthermore, risk of lung cancer did not increase with increasing duration of employment or time since hire. The study thus provides no evidence that occupational exposures at PG&E facilities resulted in increased risk of lung cancer or any other cause of death. The results indicate that any chromium exposures were of insufficient magnitude to result in increased risk of lung cancer.

The use of artificial joint implants has risen greatly over the past years. However, few investigations of the cancer risk associated with implants have been performed. We investigated cancer risk in patients with finger and hand joint and temporo-mandibular (TMJ) joint implants. A nationwide cohort in Denmark of patients with finger and hand joint prostheses (n = 858) or TMJ implants (n = 389) was followed from January 1, 1977, to December 31, 1995, to evaluate any potential cancer risks subsequent to receiving these implants. Standardized incidence ratios (SIRs) for all cancers were 1.0 (95% CI = 0.8-1.2) for the finger and hand joint cohort and 1.1 (95% CI = 0.8-1.7) for the TMJ cohort. A significant risk for non-Hodgkin's lymphoma was found in the finger and hand joint cohort (SIR = 3.8, 95% CI = 1.5-7.8). When the finger and hand joint cohort was stratified by diagnosis of rheumatoid arthritis, the excess risk was seen only in the group with rheumatoid arthritis. This is consistent with past studies, which have found an association between rheumatoid arthritis and non-Hodgkin's lymphoma. Our results provide evidence that the cancer risk for patients with finger and hand joint prostheses and TMJ implants is similar to that for the general population.

A case-control study of pancreas cancer in residents, aged 30-79 years, of 18 counties in southeastern Michigan was conducted to investigate the risks of exposure to DDT and related materials in the general population. Sixty-six people with cytologically diagnosed pancreas cancer were identified using 7 participating hospitals in metropolitan Detroit and Ann Arbor. One hundred and thirty-one controls were frequency-matched to the cases on age, sex, ethicity and county of residence by random-digit dialing. All study participants were administered a questionnaire to assess life-time exposure to pesticides from both environmental and occupational sources, family history of cancer, past medical history, smoking history and demographic information. A statistically significant increased risk was found for self-reported exposure to ethylan (1,1-dichloro-2,2-bis(4-methoxyphenyl) ethane). Increased odds ratios were observed for self-reported exposures to chloropropylate and DDT, as well as for the summary group of organochlorine pesticides which included all of these materials, though these associations were not significant.