Epidemiology of sporadic inclusion body myositis and polymyositis in Olmsted County, Minnesota

OBJECTIVE: To determine the incidence and prevalence of sporadic inclusion body myositis (sIBM) and polymyositis (PM) in a population-based study. METHODS: Charts of patients with myositis in Olmsted County, Minnesota, USA, from 1981 to 2000 were reviewed. RESULTS: For sIBM, the age- and sex-adjusted incidence rates per 100,000 were 0.79 (95% confidence interval = 0.24-1.35), and for PM, 0.41 (95% CI 0.08-0.73). The age- and sex-adjusted prevalence rates per 100,000 were 7.06 (95% CI 0.87-13.24) for sIBM and 3.45 (95% CI 0.00-7.35) for PM. CONCLUSION: The incidence and prevalence rates for sIBM are higher than previously reported.     

Update on the incidence and prevalence of Crohn's disease and ulcerative colitis in Olmsted County, Minnesota, 1940-2000

BACKGROUND: We previously reported that the prevalence of Crohn's disease (CD) and ulcerative colitis (UC) in Olmsted County, Minnesota, had risen significantly between 1940 and 1993. We sought to update the incidence and prevalence of these conditions in our region through 2000. METHODS: The Rochester Epidemiology Project allows population-based studies of disease in county residents. CD and UC were defined by previously used criteria. County residents newly diagnosed between 1990 and 2000 were identified as incidence cases, and persons with these conditions alive and residing in the county on January 1, 2001, were identified as prevalence cases. All rates were adjusted to 2000 US Census figures for whites. RESULTS: In 1990-2000 the adjusted annual incidence rates for UC and CD were 8.8 cases per 100,000 (95% confidence interval [CI], 7.2-10.5) and 7.9 per 100,000 (95% CI, 6.3-9.5), respectively, not significantly different from rates observed in 1970-1979. On January 1, 2001, there were 220 residents with CD, for an adjusted prevalence of 174 per 100,000 (95% CI, 151-197), and 269 residents with UC, for an adjusted prevalence of 214 per 100,000 (95% CI, 188-240). CONCLUSION: Although incidence rates of CD and UC increased after 1940, they have remained stable over the past 30 years. Since 1991 the prevalence of UC decreased by 7%, and the prevalence of CD increased about 31%. Extrapolating these figures to US Census data, there were approximately 1.1 million people with inflammatory bowel disease in the US in 2000.     

Epidemiology of Celiac Sprue: A Community-based Study

Objective: To address the frequency and outcome of celiac disease in a United States community. Methods: We identified all Olmsted County, Minnesota, residents diagnosed with this condition during the period, 1960 through 1990, using the resources of the Rochester Epidemiology Project. Twenty-eight incident cases (19 women, nine men) were identified. Results: The overall age- and gender-adjusted incidence of celiac disease in the community was 1.2 per 100,000 person-yr (95% CI 0.7,1.6). There were no significant changes in incidence over time, although rates did increase; the incidence was similar in men and women and rose with age in both genders ( p < 0.05). Survival in this inception cohort was 100% at 6 months and 96% at 5 yr, which was not significantly different from expected. The estimated prevalence on January 1, 1991, was 21.8 per 100,000. Conclusion: This study provides the first epi-demiologic data on celiac disease in the United States.     

Trends in the incidence of polycythemia vera among olmsted county,Minnesota residents, 1935–1989

To investigate the suggestion that the incidence of polycythemia vera has increased in recent decades, we ascertained secular trends in the incidence of polycythemia vera in Olmsted County, Minnesota, over the 55-year period, 1935–1989. The inpatient and outpatient medical records of all potential cases of polycythemia vera in Olmsted County residents were reviewed and the diagnostic criteria of the Polycythemia Vera Study Group were applied. We found no indication of an increase in the age- and sex-adjusted incidence of polycythemia vera, which averaged 1.9 per 100,000 person-years (95% C.I., 1.4–2.5) over the study period. Incidence rates increased with age, and age-adjusted incidence rates were greater for men (2.8 per 100,000 person-years; 95% C.I., 1.8–3.9) than for women (1.3 per 100,000 person-years; 95% C.I., 0.7–1.9), with the highest incidence rate (23.5 per 100,000 person-years) among men aged 70–79 years. Survival was reduced in this inception cohort of 50 cases, compared to that expected for individuals of like age and sex (P < 0.0001); median survival following diagnosis was 7.2 years. © 1994 Wiley-Liss, Inc.     

Secular Trends in Incidence and 30-Day Case Fatality of Acute Pancreatitis in North Jutland County,Denmark: A Register-based Study from 1981-2000

Background: The incidence rate of acute pancreatitis has been reported as having increased during recent decades in Western countries. Reported mortality lies around 10% and has improved during the past 20 years. The incidence rate and 30-day case fatality rate of acute pancreatitis in North Jutland County, Denmark were examined for the period 1981 to 2000. Methods: Data were collected from the Hospital Discharge Registry of North Jutland County for the period 1981-2000. Sex- and age-standardized incidence rates and 30-day case fatality rate of a first attack of acute pancreatitis were calculated. Data on endoscopic procedures were assessed for the period 1992 to 2000 and on certain drugs for 1991 to 1999. Results: The incidence rate of acute pancreatitis in women increased from 17.1 per 100,000 person-years in 1981 (95% confidence interval (CI), 12.6-23.2) to 37.8 per 100,000 person-years in 2000 (95% CI, 31.0-46.1). The corresponding increase in men was from 18 per 100,000 person-years in 1981 (95% CI, 13.3-24.2) to 27.1 per 100,000 person-years in 2000 (95% CI, 21.5-34.3). The incidence rate of acute pancreatitis increased with age in both sexes. The overall 30-day case fatality rate was 7.5% (95% CI, 6.5-8.7) increasing with age, adjusted odds ratio (OR) = 6.4 (95% CI, 3.5-11.6) and decreased with time, adjusted OR = 0.7 (95% CI, 0.4-1.0). Conclusion: The incidence of acute pancreatitis has increased, and in women surpassed that in men in 1999 and 2000. Short-term prognosis has improved.     

Secular trends in incidence and 30-day case fatality of acute pancreatitis in North Jutland County,Denmark: a register-based study from 1981-2000

BACKGROUND: The incidence rate of acute pancreatitis has been reported as having increased during recent decades in Western countries. Reported mortality lies around 10% and has improved during the past 20 years. The incidence rate and 30-day case fatality rate of acute pancreatitis in North Jutland County, Denmark were examined for the period 1981 to 2000. METHODS: Data were collected from the Hospital Discharge Registry of North Jutland County for the period 1981-2000. Sex- and age-standardized incidence rates and 30-day case fatality rate of a first attack of acute pancreatitis were calculated. Data on endoscopic procedures were assessed for the period 1992 to 2000 and on certain drugs for 1991 to 1999. RESULTS: The incidence rate of acute pancreatitis in women increased from 17.1 per 100,000 person-years in 1981 (95% confidence interval (CI), 12.6-23.2) to 37.8 per 100,000 person-years in 2000 (95% CI, 31.0-46.1). The corresponding increase in men was from 18 per 100,000 person-years in 1981 (95% CI, 13.3-24.2) to 27.1 per 100,000 person-years in 2000 (95% CI, 21.5-34.3). The incidence rate of acute pancreatitis increased with age in both sexes. The overall 30-day case fatality rate was 7.5% (95% CI, 6.5-8.7) increasing with age, adjusted odds ratio (OR) = 6.4 (95% CI, 3.5-11.6) and decreased with time, adjusted OR = 0.7 (95% CI, 0.4-1.0). CONCLUSION: The incidence of acute pancreatitis has increased, and in women surpassed that in men in 1999 and 2000. Short-term prognosis has improved.     

Increase in incidence and prevalence of inflammatory bowel disease in northern Denmark: a population-based study, 1978-2002

OBJECTIVES: Although incidence rates of inflammatory bowel disease have been reported worldwide, few long-term population-based studies with current time-trend analyses exist. We therefore examined time trends in the incidence rate of inflammatory bowel disease in a 25-year study period, and estimated the prevalence in 2002. All patients diagnosed between 1978 and 2002 were included as incident cases (n=2,326) and all patients living in North Jutland County on 31 December 2002 were used to estimate prevalent cases (n=2,205). METHODS: Medical records of all patients diagnosed with ulcerative colitis and Crohn's disease in the North Jutland County Hospital Discharge Registry were reviewed to examine if the diagnostic criteria were fulfilled. Age-specific and gender-specific standardized incidence rates were calculated. RESULTS: For ulcerative colitis, incidence rates in women increased from 8.3 (95% confidence interval (CI): 6.7-9.9) in 1978-1982 to 17.0 (95% CI: 14.7-19.3) per 100,000 person-years in 1998-2002. The corresponding figures for men were 7.7 (95% CI: 6.1-9.3) and 16.7 (95% CI: 14.4-18.8) per 100,000 person-years. For Crohn's disease, the incidence rates in women increased from 4.1 (95% CI: 3.0-5.2) in 1978-1982 to 10.7 (95% CI: 8.8-12.5) per 100,000 person-years in 1998-2002. The corresponding figures for men were 3.2 (95% CI: 2.1-4.2) and 8.5 (95% CI: 6.9-10.2) per 100,000 person-years. The prevalence of ulcerative colitis and Crohn's disease was 294 and 151 per 100,000 inhabitants, respectively. CONCLUSIONS: A marked and parallel increase was seen in both ulcerative colitis and Crohn's disease in both genders during the last 25 years, with a corresponding high prevalence of both diseases.     

Epidemiology and clinical characteristics of behçet's disease in the US: A population‐based study

Objective

Behçet's disease (BD) is a rare, multisystem inflammatory disorder of unknown cause. Although well‐documented in Eastern populations, epidemiologic data is scarce in North American countries. Here we describe the incidence and prevalence of BD in Olmsted County, Minnesota over 45 years.

Methods

We identified an incidence cohort of subjects age ≥18 years who had a clinical diagnosis of and/or fulfilled the International Study Group (ISG) criteria for BD from January 1, 1960 to January 1, 2005. Age‐ and sex‐specific incidence and prevalence were estimated and age‐ and sex‐adjusted to the 2000 US total population.

Results

The study population was comprised of 13 subjects with BD; 11 fulfilled ISG criteria between 1960 and 2005. Mean ± SD age was 31 ± 9 years, and 69% were white. Point prevalence in 2000 was 5.2 per 100,000 population (95% confidence interval [95% CI] 0.64–9.84). The overall annual age‐ and sex‐adjusted incidence of BD was 0.38 per 100,000 population (95% CI 0.17–0.59), with a higher incidence in women (0.51 per 100,000; 95% CI 0.17–0.84) than in men (0.26 per 100,000; 95% CI 0.004–0.52). Dermatologic lesions included oral ulcers (100%), genital ulcers (62%), erythema nodosum (46%), and papulopustular lesions (54%). Ocular lesions, vascular complications, and central nervous system involvement were present in 8, 3, and 3 subjects, respectively.

Conclusion

Our study shows an overall incidence of 0.38 per 100,000 population, which is comparable with other Western populations. The prevalence of 5.2 per 100,000 population is similar to estimates reported in Western countries, but lower than that in countries along the Silk Road.     

Epidemiology of polymyalgia rheumatica in olmsted county,minnesota, 1970–1991

Objective. To determine the incidence, prevalence, and survival of polymyalgia rheumatica (PMR) over a 22-year period in Olmsted County, Minnesota. Methods. Using the unified record system at the Mayo Clinic for the Olmsted County population, we reviewed all medical records with a diagnosis of PMR from 1970 through 1991. Results. There were 245 (173 female; 72 male) incidence cases of PMR between 1970 and 1991. The average annual age- and sex-adjusted incidence of PMR per 100,000 population ≥ 50 years was 52.5 (95% confidence interval [CI] 45.9–59.2), with a significantly higher incidence in females (61.7; 95% CI 52.3–71.2) than in males (39.9; 95% CI 30.7–49.2). The incidence varied over the period of observation, but no significant trends were found. The prevalence of PMR among persons ≥ 50 years on January 1, 1992 was 6/1,000. There was a small but significantly increased survival rate among male PMR patients compared with the general population. Conclusion. Our data demonstrate that PMR is a common nonfatal disease in the elderly, the incidence and clinical manifestations of which have varied but remained relatively stable over the last 2 decades.     

Ulcerative colitis in Olmsted County, Minnesota, 1940-1993: incidence, prevalence, and survival

BACKGROUND: There is significant geographic variation in the reported incidence of ulcerative colitis. AIMS: To update the incidence and prevalence of ulcerative colitis in Olmsted County, Minnesota, examine temporal trends, and determine overall survival. PATIENTS: All Olmsted County residents diagnosed with ulcerative colitis between 1940 and 1993 (incidence cases), and all residents with ulcerative colitis alive on 1 January 1991 (prevalence cases). METHODS: Incidence and prevalence rates were adjusted using 1990 US census figures for whites. The effects of age, sex, and calendar year on incidence rates were evaluated using Poisson regression. Survival from diagnosis was compared with that expected for US north-central whites. RESULTS: Between 1940 and 1993, 278 incidence cases were identified, for an adjusted incidence rate of 7.6 cases per 100 000 person years (95% confidence interval (CI), 6.7 to 8.5). On 1 January 1991, there were 218 residents with definite or probable ulcerative colitis, for an adjusted prevalence rate of 229 cases per 100 000 (95% CI, 198 to 260). Increased incidence rates were associated with later calendar years (p<0.002), younger age (p<0.0001), urban residence (p<0.0001), and male sex (p<0.003). Overall survival was similar to that expected (p>0.2). CONCLUSIONS: The overall incidence rate of ulcerative colitis in Olmsted County increased until the 1970s, and remained stable thereafter. Incidence rates among men and urban residents were significantly higher. The prevalence rate in Rochester in 1991 was 19% higher than that in 1980. Overall survival was similar to that of the general population.     

The epidemiology of microscopic colitis: a population based study in Olmsted County, Minnesota

OBJECTIVE: Although the epidemiology of microscopic colitis has been described in Europe, no such data exist from North America. We studied the incidence, prevalence and temporal trends of microscopic colitis in a geographically defined US population. DESIGN AND SETTING: In this population based cohort study, residents of Olmsted County, Minnesota, with a new diagnosis of microscopic colitis, and all who had colon biopsies for evaluation of diarrhoea, between 1 January 1985 and 31 December 2001 were identified. Biopsies were reviewed for confirmation (cases) and to identify missed cases (diarrhoea biopsies). MAIN OUTCOME MEASURES: Incidence rates, age and sex adjusted to the 2000 US white population. Poisson regression assessed the association of calendar period, age and sex with incidence. RESULTS: We identified 130 incident cases for an overall rate of 8.6 cases per 100,000 person-years. There was a significant secular trend, with incidence increasing from 1.1 per 100,000 early in the study to 19.6 per 100,000 by the end (p<0.001). Rates increased with age (p<0.001). By subtype, the incidence was 3.1 per 100,000 for collagenous colitis and 5.5 per 100,000 for lymphocytic colitis. Collagenous colitis was associated with female sex (p<0.001) but lymphocytic colitis was not. Prevalence (per 100,000 persons) on 31 December 2001 was 103.0 (39.3 for collagenous colitis and 63.7 for lymphocytic colitis). CONCLUSIONS: The incidence of microscopic colitis has increased significantly over time, and by the end of the study, the incidence and prevalence were significantly higher than reported previously. Microscopic colitis is associated with older age, and collagenous colitis is associated with female sex.     

Trends in the identification and clinical features of celiac disease in a North American community, 1950-2001.

BACKGROUND AND AIMS: Celiac disease is considered rare in North America. However, an increasing incidence and widening clinical spectrum have been reported in many countries, and serologic screening suggests a higher prevalence of minimally symptomatic disease. This study reports temporal trends in the incidence of celiac disease in Olmsted County, Minnesota. METHODS: All county residents diagnosed with celiac disease between 1950 and 2001 were identified through the Rochester Epidemiology Project. Incidence rates were calculated assuming a Poisson distribution, and changes in incidence by calendar year, age, and gender were assessed by using Poisson regression. RESULTS: Altogether, 82 new cases of celiac disease were identified during the 50-year period. There was a marked female predominance (P < 0.005), and the incidence rates increased with age (P < 0.001) and calendar period (P < 0.001). The overall annual incidence of celiac disease was 2.1 per 100,000 (95% confidence interval [CI], 1.7-2.6) but increased from 0.9 per 100,000 (CI, 0.5-1.2) in 1950-1989 to 3.3 per 100,000 (95% CI, 2.2-4.4) in the 1990s. The incidence was 9.1 per 100,000 (95% CI, 5.2-13.0) in the final 2 years of the study. Serology prompted biopsy in a substantial proportion of recent diagnoses. Clinical features also changed over time, with less diarrhea and weight loss at presentation. CONCLUSIONS: Celiac disease has increased recently in this well-characterized population. Milder clinical features and use of serology suggest an increased detection rate, although a true increase in incidence may have also occurred. Celiac disease is not rare in North America.     

Risk of intestinal cancer in inflammatory bowel disease: a population-based study from olmsted county, Minnesota

BACKGROUND & AIMS: The risk for colorectal cancer in Crohn's disease and ulcerative colitis patients from the United States currently is unknown. We estimated the risk for small-bowel and colorectal cancer in a population-based cohort of 692 inflammatory bowel disease patients from Olmsted County, Minnesota, from 1940 to 2001. METHODS: The Rochester Epidemiology Project was used to identify cohort patients with colorectal and small-bowel cancer. The cumulative probability of cancer and standardized incidence ratios (SIR) were estimated using expected rates from Surveillance, Epidemiology, and End Results, white patients from Iowa, from 1973 to 2000, and Olmsted County, from 1980 to 1999. RESULTS: Colorectal cancer was observed in 6 ulcerative colitis patients vs 5.38 expected (SIR, 1.1; 95% confidence interval [CI], 0.4-2.4), but 4 of these occurred among those with extensive colitis or pancolitis (SIR, 2.4; 95% CI, 0.6-6.0). Six Crohn's disease patients (vs 3.2 expected) developed colorectal cancer (SIR, 1.9; 95% CI, 0.7-4.1). Three Crohn's disease patients developed small-bowel cancer vs 0.07 expected (SIR, 40.6; 95% CI, 8.4-118). CONCLUSIONS: The risk for colorectal cancer was not increased among ulcerative colitis patients overall, but appeared to be increased among those with extensive colitis. The colorectal cancer risk was increased slightly among Crohn's disease patients, who also had a 40-fold excess risk for small-bowel cancer.     

Epidemiology of idiopathic dilated and hypertrophic cardiomyopathy. A population-based study in Olmsted County, Minnesota, 1975-1984

Using the records linkage system of the Mayo Clinic and of the Rochester Epidemiology Project, which accesses diagnostic data on the entire population of Olmsted County, Minnesota, we identified 45 new cases of idiopathic dilated cardiomyopathy (DCM) and 19 new cases of hypertrophic cardiomyopathy (HCM) among county residents for the years 1975-1984. Overall age- and sex-adjusted incidence rates were 6.0/100,000 and 2.5/100,000 person-years, respectively. The incidence of DCM doubled from 3.9/100,000 in the first 5 years to 7.9/100,000 person-years in the last 5 years of study. The corresponding change for HCM was from 1.4 to 3.6/100,000 person-years. Age- and sex-adjusted prevalence rates as of January 1, 1985, for DCM and HCM were 36.5/100,000 and 19.7/100,000 population, respectively. The prevalence of DCM in persons less than 55 years old was 17.9/100,000, over a third of whom were New York Heart Association functional Class III or IV at diagnosis. These estimates may be of value in determining the potential use of health care resources, particularly cardiac transplantation.     

Trends in incidence and clinical presentation of temporal arteritis in Olmsted County, Minnesota, 1950-1985

Ninety-four Olmsted County, Minnesota residents with temporal arteritis (TA) initially diagnosed between 1950 and 1985 (incidence cohort) were identified. The age- and sex-adjusted incidence of TA per 100,000 population age 50 years or older was 17.0 (95% confidence interval [CI] 13.6-20.5), with a marked increase in incidence with age and a threefold greater incidence in women (23.4, 95% CI 18.2-28.7) than in men (7.4, 95% CI 3.7-11.0). The previously described secular increase in TA incidence in Olmsted County women continued from 1970 through 1985, while TA incidence in men declined in this latter time period. Although the frequency of classic clinical manifestations of TA declined over time, the percentage of patients undergoing biopsy who have positive specimens remained relatively constant (women 41%, men 26%). The incidence rate of temporal artery biopsy also increased for women during this period, but declined for men, suggesting that the differing trends in TA incidence by sex may be partially attributable to a detection bias. Future research in TA etiology and epidemiology should focus on possible causal factors linked to the differential TA incidence by sex.     

The burden of large and small duct primary sclerosing cholangitis in adults and children: a population-based analysis

OBJECTIVES: The epidemiology of primary sclerosing cholangitis (PSC) has been incompletely assessed by population-based studies. We therefore conducted a population-based study to determine: (a) incidence rates of large and small duct PSC in adults and children, (b) the risk of inflammatory bowel disease on developing PSC, and (c) patterns of clinical presentation with the advent of magnetic resonance cholangiopancreatography (MRCP). METHODS: All residents of the Calgary Health Region diagnosed with PSC between 2000 and 2005 were identified by medical records, endoscopic, diagnostic imaging, and pathology databases. Demographic and clinical information were obtained. Incidence rates were determined and risks associated with PSC were reported as rate ratios (RR) with 95% confidence intervals (CI). RESULTS: Forty-nine PSC patients were identified for an age- and gender-adjusted annual incidence rate of 0.92 cases per 100,000 person-years. The incidence of small duct PSC was 0.15/100,000. In children the incidence rate was 0.23/100,000 compared with 1.11/100,000 in adults. PSC risk was similar in Crohn's disease (CD; RR 220.0, 95% CI 132.4-343.7) and ulcerative colitis (UC; RR 212.4, 95% CI 116.1-356.5). Autoimmune hepatitis overlap was noted in 10% of cases. MRCP diagnosed large duct PSC in one-third of cases. Delay in diagnosis was common (median 8.4 months). A minority had complications at diagnosis: cholangitis (6.1%), pancreatitis (4.1%), and cirrhosis (4.1%). CONCLUSIONS: Pediatric cases and small duct PSC are less common than adult large duct PSC. Surprisingly, the risk of developing PSC in UC and CD was similar. Autoimmune hepatitis overlap was noted in a significant minority of cases.     

Trends in incidence and clinical presentation of temporal arteritis in olmsted county,minnesota, 1950–1985

Ninety-four Olmsted County, Minnesota residents with temporal arteritis (TA) initially diagnosed between 1950 and 1985 (incidence cohort) were identified. The age- and sex-adjusted incidence of TA per 100,000 population age 50 years or older was 17.0 (95% confidence interval [CI] 13.6–20.5), with a marked increase in incidence with age and a threefold greater incidence in women (23.4, 95% CI 18.2–28.7) than in men (7.4, 95% CI 3.7–11.0). The previously described secular increase in TA incidence in Olmsted County women continued from 1970 through 1985, while TA incidence in men declined in this latter time period. Although the frequency of classic clinical manifestations of TA declined over time, the percentage of patients undergoing biopsy who have positive specimens remained relatively constant (women 41%, men 26%). The incidence rate of temporal artery biopsy also increased for women during this period, but declined for men, suggesting that the differing trends in TA incidence by sex may be partially attributable to a detection bias. Future research in TA etiology and epidemiology should focus on possible causal factors linked to the differential TA incidence by sex.     

Reappraisal of the epidemiology of giant cell arteritis in Olmsted County, Minnesota, over a fifty-year period

OBJECTIVE: To investigate time trends in the incidence and survival of giant cell arteritis (GCA) over a 50-year period in Olmsted County, Minnesota. METHODS: Using the unified record system at the Mayo Clinic, we identified all incident cases of GCA first diagnosed between 1950 and 1999. Incidence rates were estimated and adjusted to the 1980 United States white population for age and sex. The annual incidence rates were graphically illustrated using a 3-year centered moving average. Survival rates were computed and compared with the expected rates in the population. RESULTS: There were 173 incident cases of GCA during the 50-year study period. Of these, 79% were women and the mean age at diagnosis was 74.8 years. The overall age- and sex-adjusted incidence per 100,000 persons 50 years of age or older was 18.8 (95% confidence interval [95% CI] 15.9-21.6). Incidence was higher in women (24.4; 95% CI 20.3-28.6) than in men (10.3; 95% CI 6.9-13.6). Incidence rates increased significantly over the study period (P = 0.017); in particular, a progressive increase was observed from 1950 to 1979; subsequently, no substantial increases in incidence rates were observed. A cyclic pattern of annual incidence rates was apparent, with evidence of 6 peak periods. Survival among individuals with GCA was not significantly different from that expected in the population (P = 0.80). CONCLUSIONS: The incidence of GCA increased over the first 3 decades of the study, then remained stable over the last 20 years. The previously observed cyclic pattern of annual incidence rates was still apparent over a 50-year period. Overall survival in GCA was similar to that in the population.     

Epidemiology of Lyme disease in Olmsted County, MN, 1975-1990.

Lyme disease has been reported in Minnesota since 1980. Until now, it has not been regarded as endemic in Olmsted County. We reviewed the medical records of all 68 cases of Lyme disease diagnosed in residents of Olmsted County for 1980-1990. Only 17 of the 68 cases met Centers for Disease Control surveillance criteria for definite Lyme disease (13 men, 4 women). Of these 17 cases, 3 were likely acquired in Olmsted County. The age and sex adjusted incidence rate was 2.3/100,000 (95% CI 1.1-3.4). Although reporting of Lyme disease is mandatory in Minnesota, only 7 suspected or definite cases were actually reported to public health officials. Of these, 4 met the case definition. In this population Lyme disease was both over-diagnosed and underreported. This observation questions current data and could have important health policy implications if confirmed nationally.