Incidence of venous thromboembolism in hospitalized patients vs community residents.

OBJECTIVE: To estimate the incidence rates of deep venous thrombosis (DVT) and pulmonary embolism (PE) in hospitalized patients and to compare these with incidence rates in community residents. PATIENTS AND METHODS: We performed a retrospective review of the complete medical records from a population-based inception cohort of patients who resided in Olmsted County, Minnesota, and had an incident DVT or PE from 1980 through 1990. RESULTS: From 1980 through 1990, 911 Olmsted County residents experienced their first lifetime event of definite, probable, or possible venous thromboembolism. Of these residents, 253 had been hospitalized for some reason other than a diagnosis of DVT or PE (in-hospital cases), and 658 were not hospitalized at onset of venous thromboembolism (community residents). The average annual age- and sex-adjusted incidence of in-hospital venous thromboembolism was 960.5 (95% confidence interval, 795.1-1125.9) per 10,000 person-years and was more than 100 times greater than the incidence among community residents at 7.1 (95% confidence interval, 6.5-7.6) per 10,000 person-years. The incidence of venous thromboembolism rose markedly with increasing age for both groups, with PE accounting for most of the age-related increase among in-hospital cases. Incidence rates in the 2 groups changed little over time despite a reduction in the average length of hospital stay between 1980 and 1990. CONCLUSIONS: Venous thromboembolism is a major national health problem, especially among elderly hospitalized patients. This finding emphasizes the need for accurate identification of hospitalized patients at risk for venous thromboembolism and a better understanding of the mechanisms involved so that safe and effective prophylaxis can be implemented.

Hospital admissions, length of stay, charges, and in-hospital death among patients with systemic sclerosis.

OBJECTIVE: To investigate population hospitalization rates to community hospitals for systemic sclerosis (SSc, scleroderma) and examine whether age, sex, race, and insurance status independently predict length of stay (LOS), hospital charges, and in-hospital death. METHODS: The 1995 Healthcare Cost and Utilization Project national inpatient sample was used to identify 3,621 SSc hospitalizations. Weighted age, sex, and race-specific frequencies were divided by population estimates to calculate hospitalizations per million people. Regression models were used to model LOS, charges, and in-hospital death with age, sex, race, and insurance serving as the primary independent variables. Covariates included numbers of diagnoses and procedures, whether or not the admission was a transfer from another hospital, and the presence of comorbid conditions. RESULTS: Population hospitalization rates were higher for non-whites compared to whites among those < 65, while rates were higher for whites compared to non-whites for those > or =65 years old. On average, non-whites were at least 10 years younger than whites. The mean LOS was 7.5 days, with whites' average LOS being 10% shorter than non-whites', and patients with public health insurance having approximately 9% longer LOS than those with private insurance. Charges averaged almost US$15,000 per hospitalization (median = $8,441), amounting to $280 million in community hospital charges in the U.S. in 1995. The overall in-hospital death rate was 7.1%. CONCLUSION: These patterns are consistent with a greater burden and increased severity of disease among non-whites under age 65 with Ssc.

A prospective cohort study of practice guidelines in inflammatory bowel disease.

OBJECTIVES: Practice guidelines should improve care, but they are not routinely followed, in part because of lack of proven benefit. We evaluated the effect of introducing guidelines for inflammatory bowel disease (IBD) on practice variation and the IBD Quality of Life (IBDQ) score. METHODS: This was a prospective, controlled, cohort study. A total of 65 patients were matched according to month of visit, diagnosis, and disease activity with control subjects seen 1 yr earlier. Physicians were educated throughout the study regarding the guidelines. Variation was measured by the Mayo Practice Guideline Score (MPGS), a 15-point assessment of documentation of diagnosis, nutrition, social support, education, functional status, and treatment. The IBDQ was measured at baseline and at 1 yr in the intervention group and after 1 yr in the control group. RESULTS: The MPGS was significantly higher in the intervention group compared to the controls (p = 0.002), with median values of 12 versus 11. The IBDQ median score increased significantly in the intervention group (p < 0.001), baseline median of 133 versus 15-month median of 184. However, the final IBDQ was not significantly higher in the intervention group than in the controls (p = 0.33). CONCLUSIONS: Practice guidelines for IBD reduce practice variation. The quality of life improved significantly compared to baseline with practice guidelines, but not compared to controls, perhaps because of the small sample size and homogenous practice setting. The MPGS is a tool that can be used in day-to-day management of IBD patients.

School attendance and school performance: a population-based study of children with asthma.

OBJECTIVE: To analyze school attendance and school achievement as outcomes of the care of children with asthma. METHODS: A previously identified Rochester, Minnesota, cohort of children with asthma and age- and sex-matched children without asthma were studied. School attendance, standardized achievement test scores, grade point average, grade promotion, and class rank of graduating students for children with asthma and control subjects were obtained from the Rochester Public School system. RESULTS: Children with asthma (n = 92) and age- and sex-matched non-asthmatic control subjects with 640 school-years of observation were studied. Children with asthma had 2.21 (95% CI, 1.41 to 3.01) more days absent than children without asthma. There was no significant difference in standardized achievement test scores (reading percentile difference 1.22% [95% CI, -3.68 to 6.12], mathematics percentile difference 2.36% [95% CI, -2.89 to 7.60], language percentile difference 2.96% [95% CI, -4.03 to 7.15]). There was no significant difference in grade point average, grade promotion, or class rank of graduating students. CONCLUSION: In this community, although children with asthma had 2 excess days of absenteeism, the school performance of children with asthma was similar to that of children without asthma.

The epidemiology of venous thromboembolism in the community.

The incidence of venous thromboembolism exceeds 1 per 1000; over 200,000 new cases occur in the United States annually. Of these, 30% die within 30 days; one-fifth suffer sudden death due to pulmonary embolism. Despite improved prophylaxis, the incidence of venous thromboembolism has been constant since 1980. Independent risk factors for venous thromboembolism include increasing age, male gender, surgery, trauma, hospital or nursing home confinement, malignancy, neurologic disease with extremity paresis, central venous catheter/transvenous pacemaker, prior superficial vein thrombosis, and varicose veins; among women, risk factors include pregnancy, oral contraceptives, and hormone replacement therapy. About 30% of surviving cases develop recurrent venous thromboembolism within ten years. Independent predictors for recurrence include increasing age, obesity, malignant neoplasm, and extremity paresis. About 28% of cases develop venous stasis syndrome within 20 years. To reduce venous thromboembolism incidence, improve survival, and prevent recurrence and complications, patients with these characteristics should receive appropriate prophylaxis.

Trends in the incidence of venous stasis syndrome and venous ulcer: a 25-year population-based study.

BACKGROUND: The incidence rates of venous stasis syndrome and venous ulcer are uncertain, and trends in incidence are unknown. METHODS: We performed a retrospective review of the complete (inpatient and outpatient) medical records of a community population (Olmsted County, Minnesota) to estimate the incidence of venous stasis syndrome and venous ulcer during the 25-year period, 1966 to 1990, and to describe trends in incidence. RESULTS: A total of 1131 patients received a first lifetime diagnosis of venous stasis syndrome. A total of 263 patients received a first lifetime diagnosis of venous ulcer. The overall incidence of venous stasis syndrome and venous ulcer were 76.1 and 18.0 per 100,000 person-years, respectively. The incidence of both was higher in women than in men (83.7 vs 67.4 per 100,000 person-years for venous stasis syndrome; 20.4 vs 14.6 per 100,000 for venous ulcer) and increased with age for both sexes. There was no clear trend in the incidence of venous stasis syndrome over the 25-year period. Compared with 1966 to 1970, the incidence of venous ulcer decreased in 1971 to 1980, but was unchanged after 1981. Among 945 patients with venous stasis only, 60 subsequently had a venous ulcer. The average (+/- SD) time from venous stasis diagnosis to development of a venous ulcer was 5.0 (+/- 5.0) years. CONCLUSION: Venous stasis syndrome and venous ulcer are common, especially in the elderly population. The incidence of venous stasis syndrome has not changed since 1966, and venous ulcer incidence is unchanged since 1981. More accurate identification of patients at risk for venous stasis syndrome and venous ulcer and more effective prevention are needed.

Predicted impact of attaining smoking reduction goals on mortality.

The impact of reducing smoking initiation, increasing smoking cessation, and combination approaches on life expectancy, deaths averted, and life-years gained in a birth cohort of 50,000 persons and in the state population (3.6 million) were analyzed. A 60% reduction in initiation of smoking in adolescents would increase life expectancy by 0.42 years. Over the next 100 years, there would be an additional 18,000 years of life for a birth cohort and an additional 675,000 years of life for the state's population. The reduction in mortality, however, would not begin before 35 years, and only 25% of the benefit would occur in the next 70 years. An increase in smoking cessation would have a smaller impact that would occur sooner. Maximum reduction in mortality could be achieved by reducing initiation and increasing cessation at all ages, but a reduction in mortality would not occur for several decades.

Risk factors for deep vein thrombosis and pulmonary embolism during pregnancy or post partum: a population-based, case-control study.

OBJECTIVE: We sought to determine risk factors for deep vein thrombosis and pulmonary embolism during pregnancy or post partum. STUDY DESIGN: We performed a population-based case-control study. All Olmsted County, Minnesota, residents with a first lifetime deep vein thrombosis or pulmonary embolism during pregnancy or post partum from 1966 to 1990 were identified (N = 90). Where possible, a resident without deep vein thrombosis or pulmonary embolism was matched to each patient by date of the first live birth after the patient's child. The medical records of all remaining patients and all control subjects were reviewed for >25 baseline characteristics, which were tested as risk factors for deep vein thrombosis or pulmonary embolism. RESULTS: In multivariate analysis smoking (odds ratio, 2.4) and prior superficial vein thrombosis (odds ratio, 9.4) were independent risk factors for deep vein thrombosis or pulmonary thrombosis during pregnancy or post partum. CONCLUSION: Venous thromboembolism prophylaxis may be warranted for pregnant women with prior superficial vein thrombosis. Smoking cessation should be recommended, especially during pregnancy and the postpartum period.

Predicting patient intent to return from satisfaction scores.

This study describes the development of a patient satisfaction assessment instrument used at the Medical University of South Carolina Outpatient Services clinics. Three years of responses were analyzed and a logistic regression model is presented to identify components of care that predict patient intent to return for additional care. Waiting time and understanding doctor's explanation were the only items that were significant predictors of intent to return. Additionally, the calculated probability of a return visit was used to calculate the potential impact of changes in mean satisfaction scores on the number of patient visits to the hospital ambulatory clinics.

The venous stasis syndrome after deep venous thrombosis or pulmonary embolism: a population-based study.

OBJECTIVES: To estimate the incidence and determine predictors of venous stasis syndrome and venous ulcers after deep venous thrombosis and pulmonary embolism. PATIENTS AND METHODS: This population-based retrospective cohort study reviewed medical records of 1527 patients with incident deep venous thrombosis or pulmonary embolism between 1966 and 1990. We recorded baseline characteristics, event type (deep venous thrombosis with or without pulmonary embolism or pulmonary embolism alone), leg side and site of deep venous thrombosis (proximal with or without distal deep venous thrombosis vs distal deep venous thrombosis alone), and venous stasis syndrome and venous ulcer. RESULTS: Two hundred forty-five patients developed venous stasis syndrome. One-year, 5-year, 10-year, and 20-year cumulative incidence rates were 7.3%, 14.3%, 19.7%, and 26.8%, respectively. By 20 years the cumulative incidence of venous ulcers was 3.7%. Patients with deep venous thrombosis with or without pulmonary embolism were 2.4-fold (95% confidence interval, 1.7-fold-3.2-fold) more likely to develop venous stasis syndrome than patients with pulmonary embolism and no diagnosed deep venous thrombosis. In patients aged 40 years or younger with proximal compared with distal-only deep venous thrombosis, venous stasis syndrome was 3.0-fold more likely (95% confidence interval, 1.6-fold-4.7-fold). In patients with unilateral leg deep venous thrombosis, venous stasis syndrome usually developed in the concordant leg (P < .001). There was a 30% (95% confidence interval, 2%-62%) increased risk for venous ulcer per decade of age at the incident venous thromboembolism. CONCLUSIONS: The cumulative incidence of venous stasis syndrome continues to increase for 20 years after venous thromboembolism. Pulmonary embolism alone is less likely to cause venous stasis syndrome.

The canalith repositioning procedure for the treatment of benign paroxysmal positional vertigo: a randomized controlled trial.

OBJECTIVE: To compare the canalith repositioning procedure (CRP) with a sham maneuver for the treatment of benign paroxysmal positional vertigo. PATIENTS AND METHODS: We recruited 50 patients with a history of positional vertigo and unilateral positional nystagmus on physical examination (Dix-Hallpike maneuver). Patients were randomized to either the CRP (n = 24) or a sham maneuver (n = 26). Measured outcomes included resolution of vertigo and positional nystagmus at follow-up examination. RESULTS: The mean duration of follow-up was 10 days for both groups. Resolution of symptoms was reported by 12 (50%) of the 24 patients in the CRP group and by 5 (19%) of the 26 patients in the sham group (P = .02). The results of the Dix-Hallpike maneuver were negative for positional nystagmus in 16 (67%) of 24 patients in the CRP group and in 10 (38%) of 26 patients in the sham group (P = .046). CONCLUSION: The CRP is effective treatment of benign paroxysmal positional vertigo, and this procedure can be performed by general internists on outpatients with this disorder.

Antibiotics and return visits for respiratory illness: a comparison of pooled versus hierarchical statistical methods.

BACKGROUND: Antibiotic prescribing for respiratory illness has been associated with small reductions in return visits in an analysis of a large practice-based network. In this study, we apply hierarchical analytical methods that account for the clustering of patients by practices to identify whether antibiotic prescribing by primary care physicians reduces subsequent visits for 6 acute respiratory illnesses-upper respiratory infection, pharyngitis, bronchitis, otitis media, sinusitis, and cough. METHODS: The study data came from 318 family physicians and internists in 45 practices in the Practice Partner Research Network from January 1995 through December 1996, with 255,564 active patients. Patients treated with antibiotics were compared with those who were not on the frequency of revisit within the next 14 days. A simple pooling model and 3 hierarchical statistical models (fixed-effects, random-effects, and Bayesian) were used to compare the odds-ratios for return visits. RESULTS: Statistically significant results were found only for bronchitis and sinusitis by the hierarchical models, but the simple pooling model produced statistically significant results for all study conditions. CONCLUSION: We conclude that antibiotics may reduce return visits for patients with bronchitis and sinusitis, but not for patients with other respiratory illness (upper respiratory infection, pharyngitis, otitis media, or cough). Studies of large clinical databases should use methods of analysis that account for the grouping of patients by practice to avoid false positive associations (type I errors.)

Bone marrow transplantation versus periodic prophylactic blood transfusion in sickle cell patients at high risk of ischemic stroke: a decision analysis.

Measurement of cerebral blood velocity (CBV) by transcranial Doppler has been used to identify patients with sickle cell disease (SCD) who are at high risk of ischemic stroke. This study examines outcomes of bone marrow transplantation (BMT) and periodic blood transfusion (PBT) as a basis for making treatment recommendations for patients who have elevated CBV and no other indications for BMT. Decision analysis was used to compare the number of quality-adjusted life years (QALYs) experienced by a population of patients with SCD at high risk for stroke who were treated with PBT or BMT. Markov models were constructed to represent the clinical course of patients with SCD who were treated with PBT or BMT. Medical literature and expert opinion provided risks of stroke and death for different disease states, estimates of transition probabilities from one clinical state to another, and quality of life. An intention-to-treat analysis and an analysis of treatment received were both performed on hypothetical cohorts of 100 000 patients. Patients with SCD who were managed with a strategy of intending to provide BMT could expect 16.0 QALYs, compared with 15.7 QALYs for a strategy of intending to provide PBT; however, the variation around these estimates was large. In the treatment received analysis, patients compliant with PBT therapy and iron chelation could expect the best outcomes (19.2 QALYs). From a policy perspective, neither BMT nor PBT can be considered the "best" treatment for children with SCD who have abnormal CBV. Abnormal CBV should not be the only criterion for selecting patients with sickle cell for BMT.

Predictors of recurrence after deep vein thrombosis and pulmonary embolism: a population-based cohort study.

BACKGROUND: The appropriate duration of oral anticoagulation after a first episode of venous thromboembolism (VTE) is uncertain and depends upon VTE recurrence rates. OBJECTIVE: To estimate VTE recurrence rates and determine predictors of recurrence. METHODS: Patients in Olmsted County, Minnesota, with a first lifetime deep vein thrombosis or pulmonary embolism diagnosed during the 25-year period from 1966 through 1990 (N = 1,719) were followed forward in time through their complete medical records in the community for first VTE recurrence. RESULTS: Four hundred four patients developed recurrent VTE during 10,198 person-years of follow-up. The overall (probable/definite) cumulative percentages of VTE recurrence at 7, 30, and 180 days and 1 and 10 years were 1.6% (0.2%), 5.2% (1.4%), 10.1% (4.1%), 12.9% (5.6%), and 30.4% (17.6%), respectively. The risk of recurrence was greatest in the first 6 to 12 months after the initial event but never fell to zero. Independent predictors of first overall VTE recurrence included increasing age and body mass index, neurologic disease with paresis, malignant neoplasm, and neurosurgery during the period from 1966 through 1980. Independent predictors of first probable/definite recurrence included diagnostic certainty of the incident event and neurologic disease in patients with hospital-acquired VTE. Recurrence risk was increased by malignant neoplasm but varied with concomitant chemotherapy, patient age and sex, and study year. CONCLUSIONS: Venous thromboembolism recurs frequently, especially within the first 6 to 12 months, and continues to recur for at least 10 years after the initial VTE. Patients with VTE with neurologic disease and paresis or with malignant neoplasm are at increased risk for recurrence, while VTE patients with transient or reversible risk factors are at less risk.

Risk factors for deep vein thrombosis and pulmonary embolism: a population-based case-control study.

BACKGROUND: Reported risk factors for venous thromboembolism (VTE) vary widely, and the magnitude and independence of each are uncertain. OBJECTIVES: To identify independent risk factors for deep vein thrombosis and pulmonary embolism and to estimate the magnitude of risk for each. PATIENTS AND METHODS: We performed a population-based, nested, case-control study of 625 Olmsted County, Minnesota, patients with a first lifetime VTE diagnosed during the 15-year period from January 1, 1976, through December 31, 1990, and 625 Olmsted County patients without VTE. The 2 groups were matched on age, sex, calendar year, and medical record number. RESULTS: Independent risk factors for VTE included surgery (odds ratio [OR], 21.7; 95% confidence interval [CI], 9.4-49.9), trauma (OR, 12.7; 95% CI, 4.1-39.7), hospital or nursing home confinement (OR, 8.0; 95% CI, 4.5-14.2), malignant neoplasm with (OR, 6.5; 95% CI, 2.1-20.2) or without (OR, 4.1; 95% CI, 1.9-8.5) chemotherapy, central venous catheter or pacemaker (OR, 5.6; 95% CI, 1.6-19.6), superficial vein thrombosis (OR, 4.3; 95% CI, 1.8-10.6), and neurological disease with extremity paresis (OR, 3.0; 95% CI, 1.3-7.4). The risk associated with varicose veins diminished with age (for age 45 years: OR, 4.2; 95% CI, 1.6-11.3; for age 60 years: OR, 1.9; 95% CI, 1.0-3.6; for age 75 years: OR, 0.9; 95% CI, 0.6-1.4), while patients with liver disease had a reduced risk (OR, 0.1; 95% CI, 0.0-0.7). CONCLUSION: Hospital or nursing home confinement, surgery, trauma, malignant neoplasm, chemotherapy, neurologic disease with paresis, central venous catheter or pacemaker, varicose veins, and superficial vein thrombosis are independent and important risk factors for VTE.

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.

Colorectal cancer screening: a community case-control study of proctosigmoidoscopy, barium enema radiography, and fecal occult blood test efficacy.

OBJECTIVE: To examine the effectiveness of screening proctosigmoidoscopy, barium enema radiography, and the fecal occult blood test (FOBT) in decreasing colorectal cancer mortality in a community setting. PATIENTS AND METHODS: In this population-based case-control study, cases comprised 218 Rochester, Minn, residents who died of colorectal cancer between 1970 and 1993. Controls were 435 age- and sex-matched residents who did not have a diagnosis of colorectal cancer. Screening proctosigmoidoscopy, barium enema radiography, and FOBT results were documented for the 10 years prior to and including the date of diagnosis of fatal colorectal cancer in cases and for the same period in matched controls. History of general medical examinations and hospitalizations was also recorded. RESULTS: Within the 10 years prior to diagnosis, the percentages of cases vs controls with at least 1 screening proctosigmoidoscopy were 23 (10.6%) of 218 cases vs 43 (9.9%) of 435 controls; at least 1 screening barium enema radiographic study was done in 12 (5.5%) of 218 vs 25 (5.7%) of 435. Within 3 years prior to diagnosis, the percentages of cases vs controls with at least 1 screening FOBT were 27 (12.4%) of 218 vs 44 (10.1%) of 435. Adjusted odds ratios were 1.04 (95% confidence interval [CI], 0.21-5.13) for proctosigmoidoscopy (distal rectosigmoid cancers only), 0.67 (95% CI, 0.31-1.48) for barium enema radiography, and 0.83 (95% CI, 0.45-1.52) for FOBT over the above time periods. CONCLUSION: In this case-control study within a community setting, a colorectal cancer-specific mortality benefit could not be demonstrated for screening by FOBT, proctosigmoidoscopy, or barium enema radiography. Screening frequency was low, which may have contributed to the lack of measurable effects.

Costs, charges, and reimbursements for persons with sickle cell disease.

PURPOSE: The aims of this study were to describe health care costs and charges for patients with sickle cell disease (SCD) and identify predictors of high use. PATIENTS AND METHODS: Patients with SCD were identified by International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) codes from a university hospital's administrative databases from January 1, 1996, to September 30, 1997. Clinical and administrative data were gathered on each patient for all hospital admissions and ambulatory clinic visits. Logistic regression models were used to determine predictors of high health care use. RESULTS: A total of 947 patients with SCD were identified, 73% of whom resided within three South Carolina counties. On average, there were 0.9 admissions per patient per year and 8.0 outpatient visits per patient per year. Mean inpatient hospital charges, physician charges, and direct hospital costs per admission were $7290, $1589, and $5405, respectively, and the average length of stay was 4.5 days. Mean hospital charges, physician charges, and direct hospital costs per outpatient visit were $305, $169, and $688, respectively. Forty percent of the inpatient hospital charges were accounted for by only 4.2% of the patients. Residing in a distant county and being admitted with a diagnosis of painful respiration were found to be predictors of excessive charges and expenses beyond expected reimbursements. CONCLUSIONS: Patients with SCD are frequent users of health care services. Charges and costs are distributed disproportionately across these patients. Predictors of excessive hospital charges include living geographically distant from the hospital and being admitted with a diagnosis of painful respiration.

Epidemiology of anaphylaxis in Olmsted County: A population-based study.

BACKGROUND: Awareness of the clinical features of anaphylaxis and its causative triggers is important if recurrent episodes are to be avoided. The incidence of anaphylaxis in the general population is often underreported, and epidemiologic studies are few. Because an accurate profile of anaphylaxis could heighten awareness of this problem, we investigated the epidemiology of anaphylaxis in the general population of Olmsted County, Minn. OBJECTIVE: The purpose of this study was to describe the epidemiology of anaphylaxis in Olmsted County residents from 1983 through 1987. METHODS: This was a retrospective population-based cohort study. The medical records of 1255 Olmsted County residents identified by computer-linked, medical diagnostic indices (the Rochester Epidemiology Study) were reviewed retrospectively to identify residents whose clinical episodes met the criteria for anaphylaxis. We determined the incidence and rate of occurrence of anaphylaxis, rate of recurrence, prevalence of atopy, cause of anaphylaxis, frequency of referral to an allergy specialist, hospital admission rate, and case-fatality rate. RESULTS: There were 133 residents who experienced 154 anaphylactic episodes during the 5-year period: 116 residents had 1 episode of anaphylaxis, 13 residents had 2 episodes, and 4 residents had 3 episodes. The anaphylaxis occurrence rate was 30 per 100,000 person-years (95% confidence interval, 25-35). There were 110 residents who had a first lifetime episode of anaphylaxis (that was medically evaluated) during the years 1983 to 1987. The average annual incidence rate of anaphylaxis was 21 per 100,000 person-years (95% confidence interval, 17-25). Atopy was present in 53% of the cohort, and allergy consultation was obtained in 52%. A suspect allergen was identified in 68% of the cohort, most frequently a food, medication, or insect sting. The hospitalization rate was 7%, and 1 patient died. CONCLUSION: The incidence of anaphylaxis is less than 1%, and death rarely occurs. People with atopy experience anaphylaxis more frequently than people without atopy. Anaphylaxis frequently is not recognized by patients and physicians.

Long-term use of oral anticoagulants and the risk of fracture.

BACKGROUND: Vitamin K participates in bone metabolism and, since oral anticoagulants antagonize vitamin K, their use may increase the risk of osteoporosis. OBJECTIVE: To evaluate fracture risk at all skeletal sites following exposure to oral anticoagulants. METHODS: In a population-based retrospective cohort study, 572 Olmsted County, Minnesota, women 35 years or older at their first lifetime venous thromboembolism event between 1966 and 1990 were followed up for fractures. Risk was assessed by comparing new fractures with the number expected from sex- and age-specific fracture incidence rates for the general population (standardized incidence ratio [SIR]). RESULTS: Altogether, 480 fractures occurred during 6314 person-years of follow-up. Increasing exposure to oral anticoagulation was associated with an increased SIR for vertebral fractures: at less than 3 months of exposure, 2.4 (95% confidence interval [CI], 1.6-3.4); 3 to less than 12 months, 3.6 (95% CI, 2.5-4.9); and 12 months or more, 5.3 (95% CI, 3.4-8.0); and for rib fractures: at less than 3 months, 1.6 (95% CI, 0.9-2.7); 3 to less than 12 months, 1.6 (95% CI, 0.9-2.6); and 12 months or more, 3.4 (95% CI, 1.8-5.7). The data revealed no increased risk for other types of fractures. Oral anticoagulation for 12 months or more was an independent predictor of vertebral fractures (P = .009) and rib fractures (P = .02), but not other fractures. CONCLUSIONS: Long-term exposure to oral anticoagulation is associated with an increased risk of vertebral and rib fractures. The mechanism by which this occurs is still unclear and needs further investigation.