Fifty-year trend in incidence rates of bronchogenic carcinoma by cell type in Olmsted County, Minnesota.

An earlier report suggested that incidence rates of primary bronchogenic carcinoma had leveled off for men in Olmsted County, MN. Extension of that study to cover 50 years in this midwestern community now shows that lung cancer incidence continues to increase in both sexes, with rates in women approaching those found in men 20 years ago. This increase was seen for all cell types of bronchogenic carcinoma. Because one pathologist reevaluated tissues, changing histologic classifications were not responsible for secular trends; nor were the results influenced by referral bias inasmuch as the study was population based.

Incidence of multiple myeloma in Olmsted County, Minnesota: 1978 through 1990, with a review of the trend since 1945.

PURPOSE: Incidence rates of multiple myeloma appear to have increased in recent decades, but it is difficult to compare the incidence rates over time because of changes in laboratory procedures, differences in diagnostic criteria, and variations in indexing of medical records. However, Olmsted County, Minnesota, provides a rare opportunity to minimize these limitations, because the medical care has been provided mainly by the Mayo Clinic. PATIENTS AND METHODS: Records of Olmsted County residents with a diagnosis of multiple myeloma from January 1, 1978 through December 31, 1990 were reviewed. Criteria for diagnosis and residency were the same as in previous Olmsted County studies. RESULTS: The incidence rate per 100,000 age-adjusted to the 1950 United States white population was 5.4 for males and 2.8 for females; the overall rate was 4.1. The rates were age-adjusted to the 1950 United States population for comparison with earlier data from this population. The rates increased with age for both sexes. There was no significant change in incidence rates from 1945 through 1990. A comparison of the median age for Olmsted County patients with the age of those referred to the Mayo Clinic from elsewhere indicated that the local patients were appreciably older (74 v. 62 years, respectively). Thirty-two of 55 patients (58%) with multiple myeloma from 1978 through 1990 had a monoclonal plasma-cell proliferative process before the diagnosis of multiple myeloma. CONCLUSION: The incidence rate of multiple myeloma in Olmsted County, Minnesota, has not changed significantly during the past 46 years. We believe that reports of increasing rates over time are mainly due to improved case ascertainment.

Therapeutic radiation and hyperparathyroidism. A case-control study in Rochester, Minn.

A case-control study was conducted among residents of Rochester, Minn, to assess the influence of prior therapeutic radiation on the risk of primary hyperparathyroidism. Fifty-one cases of surgically proven primary hyperparathyroidism diagnosed from 1975 through 1983 were each matched by age and gender to two control subjects, with radiation exposure documented through preexisting medical records. The overall odds ratio for any prior therapeutic radiation therapy was 1.9 (95% confidence interval, 0.9 to 4.4) and it was 2.3 (95% confidence interval, 0.9 to 5.7) when limited to those with prior head and neck radiation. Among women, the figures were 2.9 (95% confidence interval, 1.1 to 7.5) for any prior therapeutic radiation and 3.4 (95% confidence interval, 1.2 to 10.2) for head and neck exposure. This study confirms the association between primary hyperparathyroidism and prior therapeutic radiation exposure, at least for women in this population.

Ascertainment of risk factors for osteoporosis: comparison of interview data with medical record review.

To determine the accuracy of self-reported risk factors for osteoporosis, an age-stratified random sample of Rochester, MN, women was studied. Results from a structured face-to-face interview were compared with information documented in contemporary inpatient and outpatient health care records in the community. Using the kappa statistic to evaluate concordance of these two data sources, we found substantial agreement for a history of proximal femoral and distal forearm fractures, peptic ulcer disease, estrogen replacement therapy and oral contraceptive use, and cigarette and alcohol exposure. Moderate agreement was seen for histories of other age-related fractures, hysterectomy or oophorectomy, thyroidectomy, and use of thyroid supplements. Poor agreement was found for prior thyroid disease, gastrectomy, and corticosteroid or anticonvulsant use. This study demonstrates a need for greater attention to the quality of self-reported risk factor data in studies of bone loss and fractures.

50-year trends in the incidence of anorexia nervosa in Rochester, Minn.: a population-based study.

OBJECTIVE: The aim of the study was to determine incidence and prevalence rates and long-term trends in incidence of anorexia nervosa by identifying all persons residing in the community of Rochester, Minn., during the 50-year period 1935 through 1984 who had the disorder. METHOD: From a community-based epidemiologic resource, 13,559 medical records with diagnoses of amenorrhea, starvation, weight loss, anorexia nervosa, or other conditions were screened to identify true cases of anorexia nervosa determined by using standard diagnostic criteria. RESULTS: One hundred eighty-one residents (166 female and 15 male) fulfilled the diagnostic criteria for anorexia nervosa; these were the incidence cases. Due to a quadratic trend in the rates for girls 10-19 years old, the incidence rate among female residents fell from 16.6 per 100,000 person-years in the 1935-1939 period to a low of 7.0 in 1950-1954 and increased to 26.3 in 1980-1984. The incidence rates for women 20 years old and older and for males remained constant. For females 15-24 years old, there was a linear increase. The overall age-adjusted incidence rate per 100,000 person-years was 14.6 for females and 1.8 for males. The prevalence rate per 100,000 population was 269.9 for females and 22.5 for males. CONCLUSIONS: Anorexia nervosa is more common than previously recognized. Among girls 15-19 years old it is a very common chronic illness. Its incidence has increased among females 15-24 years old but not among older women or among males.

Tuberous sclerosis complex in Olmsted County, Minnesota, 1950-1989.

The incidence of tuberous sclerosis complex in Olmsted County, Minnesota, was 0.28 per 100,000 person-years from 1950 through 1989, the point prevalence on December 31, 1989, was 6.9 per 100,000 persons, and the incidence at birth was 6.0 per 100,000 live births. The incidence was 0.13 per 100,000 person-years from 1950 through 1974 and 0.46 per 100,000 person-years from 1975 through 1989. The higher rate of diagnosis during the later period is believed to be due to the use of computed tomography. Of the 12 patients considered in this study, one patient presented with seizures and severe intellectual disability, six patients presented with seizures, three patients presented with multiple facial angiofibroma, and two patients were asymptomatic.

Incidence and prevalence of Huntington's disease in Olmsted County, Minnesota (1950 through 1989).

OBJECTIVE: To calculate average annual incidence rates for Huntington's disease (HD) from 1950 through 1989 and to estimate prevalence rates of the disease for January 1, 1960, and January 1, 1990. DESIGN: Health care records from all sources, including hospitals, outpatient clinics, and long-term care institutions, are readily available for all inhabitants of Olmsted County, Minnesota. The diagnoses entered in these records have been coded and indexed. All health care records containing a diagnosis that might suggest HD were reviewed, and those patients for whom the symptoms of HD began between January 1, 1950, and December 31, 1989, were identified. We used specific criteria for diagnosing HD. PARTICIPANTS: Health care records were reviewed; residence in Olmsted County during the year of symptom onset was required. MAIN OUTCOME MEASURES: Average annual incidence rates and prevalence rates for January 1, 1960, and January 1, 1990. RESULTS: Overall incidence rates were 0.4 (95% confidence interval [CI], 0.1 to 0.8) for women and 0.2 (95% CI, 0.04 to 0.6) for men per 100,000 person-years. Estimated prevalence rates for January 1, 1960, per 100,000 person-years were 6 (95% CI, 0.7 to 21.5) for women and 6.6 (95% CI, 0.8 to 23.8) for men. For January 1, 1990, the prevalence rates were 1.8 (95% CI, 0.04 to 10.2) for women and 2 (95% CI, 0.05 to 10.9) for men. CONCLUSIONS: Incidence and prevalence rates of HD in this community are similar to those reported in other communities. The small numbers of affected persons do not allow an estimate of variation over time.

Is the prevalence of dementia changing?

We compared the point prevalence rates of dementing illnesses in the population of Rochester, Minnesota, on January 1, 1980, with the previously published rates of January 1, 1975, by using extensive health care records available from all sources of care in the community, in order to identify and classify cases with standard diagnostic criteria derived from DSM-III. The overall age- and sex-adjusted prevalence rate per 100,000 population for dementia on January 1, 1980, was 402.5 compared with 388.4 on January 1, 1975; for Alzheimer's disease it was 259.8 in 1980 and 259.5 in 1975. The stability of the rates suggests no change in the incidence and mortality associated with these conditions. The prevalence rates for Rochester, Minnesota, are similar to many other rates estimated in other North American communities, but they differ from two other population-based estimates from East Boston and California. Case definitions and methods of assessment probably account for the differences in estimated prevalence.

Lack of association between Alzheimer's disease and education, occupation, marital status, or living arrangement.

Using the resources of the Rochester Epidemiology Project, we conducted a case-control study of sociodemographic characteristics using the incidence cohort of patients with Alzheimer's disease (AD). During the conduct of ongoing studies of AD in Rochester, we identified new cases of AD as they occurred during 1975-1979 (N = 241). We selected one age- and sex-matched control from among all registrations for care in this community during the year of onset for each case. There was little difference between cases and controls for educational attainment, marital status, type of dwelling, living arrangement, or occupation. We were unable to confirm low educational level as a risk factor for AD in this population. Future attempts to identify etiologic risk factors for dementing illness should probably move toward other areas of research.

Prevalence of medically diagnosed dementia in a defined United States population: Rochester, Minnesota, January 1, 1975.

Using the centralized diagnostic data resource for the population of Rochester, Minnesota, we determined the prevalence of medically diagnosed dementia for this community. There were 289 individuals with dementia who were residing in Rochester on January 1, 1975: 208 women and 81 men. The overall age- and sex-adjusted rates per 100,000 population were 342 for all dementias and 227 for Alzheimer's disease. Prevalence rates increased with age for both sexes. Limiting the denominator to persons greater than or equal to 65 years, age-adjusted rates per 100,000 population for men and women were 3,452 and 3,466 (or about 3.5%), respectively, for dementia and 2,007 and 2,675 (2.0 and 2.7%), respectively, for Alzheimer's disease.

Head trauma with loss of consciousness as a risk factor for Alzheimer's disease.

We identified all incident cases of clinically diagnosed Alzheimer's disease among the population of Rochester, MN, with onset from 1965 through 1974. A control (selected from the same community) was matched to each case by age, race, sex, and length of stay in Rochester. We studied 274 case-control pairs. Using the records linkage system available for residents of this community, we abstracted information on the occurrence of head trauma with loss of consciousness (LOC) from the medical records of both cases and controls. There were 5 pairs in which the case suffered an episode of head trauma with LOC but the control did not, and 4 pairs in which the control suffered an episode of head trauma with LOC but the case did not. We failed to detect a statistically significant difference between the 2 groups. This study overcomes many problems encountered in previous case-control studies reporting this association. The sample size was large; severity of head injury was documented in high-quality medical records; data about head injury were recorded before the onset of dementia: equal quality of data were available for cases and controls; and, since the study was population-based, there was no selection bias for cases or controls.

Is the incidence of dementing illness changing? A 25-year time trend study in Rochester, Minnesota (1960-1984)

We performed a time trend study of incidence of dementing illness in Rochester, Minnesota. We ascertained age- and sex-specific incidence rates for the five quinquennia, 1960 through 1984. The incidence rates sharply increased with advancing age, reaching a high of 2,922/100,000 person years in the group 85 years and older. For dementia caused either solely or predominantly by Alzheimer's disease, this figure was 2,600/100,000 person years for the oldest age group. There were no significant differences in the incidence of dementing illness between men and women. In the oldest age groups in the last two quinquennia of study, there appears to be a trend toward increasing incidence rates. Over the years, the proportion of cases attributed to dementia due to unknown causes has decreased while the proportion of cases attributed to Alzheimer's disease has increased.

Clinical risk factors for Alzheimer's disease: a population-based case-control study.

Using information on clinical risk factors provided through the medical record linkage system of the Rochester Epidemiology Project, we conducted a population-based case-control study of Alzheimer's disease (AD). During the period 1960 to 1974, we identified 415 newly diagnosed cases of AD among residents of Rochester, Minnesota, and matched one community control to each case based on age, sex, and duration of community medical record. We estimated odds ratios using conditional logistic regression for several potential clinical risk factors of AD. Among more than 20 clinical risk factors that were evaluated, the only statistically significant findings were for episodic depression, personality disorder, and hypertension.

The association between Alzheimer's disease and thyroid disease in Rochester, Minnesota.

To determine whether an association exists between Alzheimer's disease (AD) and thyroid disease, we carried out two studies in the population of Rochester, Minnesota. We reviewed medical records of a cohort of 198 women with histologically confirmed Hashimoto's thyroiditis (1935 to 1974) for evidence of subsequent dementia, applying the criteria used for dementia in a previous determination of incidence and prevalence rates in this population. From a total of 4,197 person-years of follow-up, eight cases of AD were diagnosed, whereas the expected number was 5.8. The standardized morbidity ratio was 1.37, which failed to reach statistical significance. The second study was a retrospective case-control comparison that sought any relationship between AD and all thyroid disorders, using a previously identified (1960 to 1979) AD cohort (N = 646) and their age- and sex-matched controls. For myxedema there was a positive association for AD without significance, whereas in Graves' disease there was a significant negative association for AD.

The prevalence of dementia is changing over time in Rochester, Minnesota.

Resources of the Rochester Epidemiology Project were used to estimate prevalence rates for dementia on January 1, 1975, 1980, and 1985, and to evaluate trends over time. Prevalence rates increased with age for both men and women. There was no difference in the prevalence rates for January 1, 1975, and January 1, 1980, but there was a significant increase between January 1, 1980, and January 1, 1985. Similar results were found for Alzheimer's disease. Age was an important factor in the trend data. The apparent increase in prevalence over time is probably multifactorial.

Dementia after ischemic stroke: a population-based study in Rochester, Minnesota (1960-1984)

We used the medical records linkage system for the population of Rochester, Minnesota, to identify persons in the community who had their first cerebral infarct without previous dementia. In this cohort (n = 971), the incidence of dementia in the first year was nine times greater than expected, but if we did not observe dementia in the first year, the risk of dementia in the cohort each year thereafter was about twice the risk in the population. After the first year, a 50% increase was observed in Alzheimer's disease in the cohort compared with that in the community. Although the incidence of dementia increased with increasing age, the standardized morbidity ratios decreased with increasing age. Age, sex (male), and second stroke were significant independent predictors of dementia in a multivariate Cox proportional hazards model. There was no effect of location or clinical severity of infarct on the rate of occurrence of dementia.

Are patients with Alzheimer's disease surviving longer in recent years?

We report the survival experience of the incidence cohort of Alzheimer's disease (AD) patients in Rochester, Minnesota, whose onset occurred during the years 1960 to 1984. Survival was evaluated relative to year of onset, age at onset, and gender. Survival was better among women than men and improved for those with AD with more recent onset. The relative hazard decreased by a factor of 0.82 for each decade. The effect of age at onset was nonlinear, indicating that the hazard of death does not change at a constant rate with age.

Prior blood transfusions and Alzheimer's disease.

We performed a population-based, case-control study to evaluate prior blood transfusion as a potential risk factor for Alzheimer's disease (AD). All cases were incident cases of AD from 1975 to 1984 with residence for 40 years or more in Olmsted County, Minnesota, prior to their onset of dementia (N = 252). There was one age- and gender-matched control for each case. We ascertained the number of blood transfusions prior to the age of onset of dementia and the corresponding year in each control. Sixty-five cases and 55 controls had at least one prior blood transfusion. We did not find a significantly increased risk of AD for the events of at least one, three, or six blood transfusions.

Familial adult motor neuron disease: amyotrophic lateral sclerosis.

We analyzed the medical records of 103 patients with familial adult motor neuron disease (MND). In the 72 families, 329 members were known to be affected. Observations were compared with the sporadic and Mariana forms of MND. Clinical and laboratory examinations of all three forms were similar in clinical course and findings, but there were minor variations in age at onset, sex ratio, survival, and the frequency with which onset occurred in the lower extremities. Recognition of the familial form still depends on diagnosis of the disease in more than one member of a family.

Alzheimer's disease and prior therapeutic radiation exposure: a case-control study.

Few risk factors have been identified for dementing illness to date. To evaluate prior therapeutic radiation exposure as a potential risk factor for Alzheimer's disease, we carried out a retrospective case-control study using the Rochester Epidemiology Resource. Cases were all incident cases of AD from 1960 through 1974 (N = 392) identified in an ongoing study of the condition in this community. One age- and sex-matched control for each case was selected from all registrations for care during the year of onset in the case. There were 86 cases and 89 controls with prior radiation exposure, and the variable used to describe exposure was absorbed dose. Most of the exposure was small doses: 11 individuals received greater than 1,000 centigray (3 cases, 8 controls). Using the logistic regression methods of Breslow and Day, the estimated odds ratio for any prior therapeutic radiation exposure was 0.95 (95% CI, 0.66 to 1.37). When the exposure variable was limited to head exposure only, the odds ratio was 0.65 (95% CI, 0.32 to 1.31). It is unlikely that the risk associated with therapeutic radiation in the development of Alzheimer's disease is greater than 1.4.