Accuracy of family history information on epilepsy and other seizure disorders

BACKGROUND

In epilepsy as in other disorders, family history information is often obtained by asking patients about the medical histories of their relatives rather than interviewing or examining the relatives directly. The accuracy of this type of information for epilepsy and other seizure disorders is unclear.

METHODS

This study used data from the Genetic Epidemiology of Seizure Disorders in Rochester study, a population-based investigation including all Rochester, MN, residents born ≥1920 with incidence of unprovoked seizures from 1935 to 1994 (case probands) and control probands matched by age, gender, and prior Rochester residency period. Seizure disorders in the first-degree relatives of case and control probands were ascertained by reviewing the relatives' medical records. Case and control probands were interviewed about seizures in their first-degree relatives using a validated 9-question screening interview. Interviewers were blinded to case-control status.

RESULTS

Sensitivity of the family history (i.e., proportion of relatives with medical record-documented seizures who screened positive in the proband interview) was 62% (32/52) for epilepsy, 50% (7/14) for isolated unprovoked seizures, and 56% (9/16) for febrile seizures. Sensitivity did not differ by case/control status of the proband. Sensitivity was much higher for probands reporting on their offspring or siblings than their parents. Among relatives with epilepsy, 90% of offspring and 80% of siblings but only 32% of parents screened positive.

CONCLUSIONS

Family histories of epilepsy are reasonably accurate for siblings and offspring, but are underreported in parents. Family histories of other seizure disorders are underreported.

Secular trends in hip fracture incidence and recurrence

The decline in hip fracture incidence is now accompanied by a further reduction in the likelihood of a recurrent hip fracture among survivors of the first fracture.

INTRODUCTION

Hip fracture incidence is declining in North America, but trends in hip fracture recurrence have not been described.

METHODS

All hip fracture events among Olmsted County, Minnesota residents in 1980-2006 were identified. Secular trends were assessed using Poisson regression, and predictors of recurrence were evaluated with Andersen-Gill time-to-fracture regression models.

RESULTS

Altogether, 2,752 hip fractures (median age, 83 years; 76% female) were observed, including 311 recurrences. Between 1980 and 2006, the incidence of a first-ever hip fracture declined by 1.37%/year for women (p < 0.001) and 0.06%/year for men (p = 0.917). Among 2,434 residents with a first-ever hip fracture, the cumulative incidence of a second hip fracture after 10 years was 11% in women and 6% in men with death treated as a competing risk. Age and calendar year of fracture were independently associated with hip fracture recurrence. Accounting for the reduction in first-ever hip fracture rates over time, hip fracture recurrence appeared to decline after 1997.

CONCLUSION

A recent reduction in hip fracture recurrence is somewhat greater than expected from the declining incidence of hip fractures generally. Additional research is needed to determine the extent to which this can be attributed to improved patient management.

Mortality in amnestic mild cognitive impairment: a prospective community study

OBJECTIVE

To assess the hazard of death in persons with and without amnestic mild cognitive impairment (aMCI).

METHODS

From 1987 through 2003, persons with aMCI (n = 243) and an age- and gender-matched reference group of cognitively normal persons in Olmsted County, MN, were recruited through the Mayo Clinic Alzheimer's Disease Patient Registry and followed prospectively through 2004. Survival was estimated using Kaplan-Meier survival curves, and the hazard of death for the aMCI cohort vs the reference cohort was estimated using Cox proportional hazards models.

RESULTS

Over a median follow-up of 5.7 years, persons with aMCI had increased mortality (hazard ratio [HR] = 1.7; 95% CI: 1.3 to 2.3) vs reference subjects. The hazard of death by aMCI subtype was 1.5 in persons with single-domain aMCI (95% CI: 1.1 to 2.1) and 2.9 in persons with multiple-domain aMCI (95% CI: 1.9 to 4.6) vs reference subjects. Analyses restricted to aMCI cases showed an interaction between aMCI subtype and APOE-epsilon4 allele status (p = 0.003). Among aMCI cases with an APOE-epsilon4 allele, there was no difference in mortality between single- and multiple-domain aMCI (HR = 1.2; 95% CI: 0.6 to 2.3). However, among aMCI cases with no APOE-epsilon4 allele, the hazard of death in multiple-domain aMCI was 4.6 (95% CI: 2.3 to 9.1) vs single-domain aMCI.

CONCLUSIONS

Amnestic mild cognitive impairment is associated with increased mortality, which is greater in multiple-domain aMCI than in single-domain aMCI. Mortality in aMCI subtypes may vary by APOE-epsilon4 allele status.

Renal stone epidemiology in Rochester, Minnesota: an update

Studies in Western countries have suggested an increasing incidence of nephrolithiasis (NL) in the latter part of the 20th century. Therefore, we updated NL epidemiology data for the Rochester population over the years 1970-2000. All Rochester residents with any diagnostic code that could be linked to NL in the years of 1970, 1980, 1990, and 2000 were identified, and the records reviewed to determine if they met the criteria for a symptomatic kidney stone as defined in a previous Rochester, MN study. Age-adjusted incidence (+/-s.e.) of new onset symptomatic stone disease for men was 155.1 (+/-28.5) and 105.0 (+/-16.8) per 100,000 per year in 1970 and 2000, respectively. For women, the corresponding rates were 43.2 (+/-14.0) and 68.4 (+/-12.3) per 100,000 per year, respectively. On average, rates for women increased by about 1.9% per year (P=0.064), whereas rates for men declined by 1.7% per year (P=0.019). The overall man to woman ratio decreased from 3.1 to 1.3 during the 30 years (P=0.006). Incident stone rates were highest for men aged 60-69 years, whereas for women, they plateaued after age 30. Therefore, since 1970 overall NL incidence rates in Rochester have remained relatively flat. However, NL rates for men have declined, whereas rates for women appear to be increasing. The reasons remain to be determined.

Direct medical costs attributable to osteoporotic fractures

Osteoporotic fractures are a major cause of morbidity in the elderly, the most rapidly growing segment of our population. We characterized the incremental direct medical costs following such fractures in a population-based cohort of men and women in Olmsted County, Minnesota. Cases included all County residents 50 years of age and older with an incident fracture due to minimal or moderate trauma between January 1, 1989 and January 1, 1992. For each case, a control of the same age (+/- 1 year) and sex who was attended in the local medical system in the same year was identified. Total incremental costs (cases - controls) in the year after fracture were estimated. Unit costs for each health service/procedure were obtained through the Mayo Cost Data Warehouse, which provides a standardized, inflation-adjusted estimate reflecting the national average cost of providing the service. Regression analysis was used to identify factors associated with incremental costs. There were 1263 case/control pairs; their average age was 73.8 years and 78% were female. Median total direct medical costs were $761 and $625, respectively, for cases and nonfracture controls in the year prior to fracture, and $3884 and $712, respectively, in the year following fracture. The highest median incremental costs were for distal femur ($11756) and hip fractures ($11241), whereas the lowest were for rib fractures ($213). Although hip fractures resulted in more incremental cost than any other fracture type, this amounted to only 37% of the total incremental cost of all moderate-trauma fractures combined. Regression analyses revealed that age, prior year costs and type of fracture were significant predictors of incremental costs (p<0.03 for all comparisons). The incremental costs of osteoporotic fractures are therefore substantial. Whereas hip fractures contributed disproportionately, they accounted for only one-third of the total incremental cost of fractures in our cohort. The use of incremental costs in economic analyses will provide a more accurate reflection of the true cost-effectiveness of osteoporosis prevention.

Temporal trends in BMI among adults with diabetes

OBJECTIVE

Increasing obesity within the general population has been accompanied by rising rates of diabetes. The extent to which obesity has increased among people with diabetes is unknown, as are the potential consequences for diabetes outcomes.

RESEARCH DESIGN AND METHODS

Community medical records (hospital and ambulatory) of all Rochester, Minnesota, residents aged > or =30 years who first met standardized research criteria for diabetes from 1970 to 1989 (n = 1,306) were reviewed to obtain data on BMI and related characteristics as of the diabetes identification date (+/-3 months). Vital status as of 31 December 1999 and date of death for those who died were obtained from medical records, State of Minnesota death tapes, and active follow-up.

RESULTS

As of the identification date, data on BMI were available for 1,290 cases. Of the 272 who first met diabetes criteria in 1970-1974, 33% were obese (BMI > or =30), including 5% who were extremely obese (BMI > or =40). These proportions increased to 49% (P < 0.001) and 9% (P = 0.012), respectively, for the 426 residents who first met diabetes criteria in 1985-1989. BMI increased significantly with increasing calendar year of diabetes identification in multivariable regression analysis. Analysis of survival revealed an increased hazard of mortality for BMI > or =41, relative to BMI of 23-25 (hazard ratio 1.60, 95% CI 1.09-2.34, P = 0.016).

CONCLUSIONS

The prevalence of obesity and extreme obesity among individuals at the time they first met criteria for diabetes has increased over time. This is disturbing in light of the finding that diabetic individuals who are extremely obese are at increased risk of mortality compared with their nonobese diabetic counterparts.

The impact of stroke on the cost and level of care in nursing homes: a retrospective population-based study

OBJECTIVE

To estimate the impact of incident stroke on nursing home (NH) costs and level of care.

SUBJECTS AND METHODS

This retrospective population-based cohort study is part of a larger study that identified all Rochester, Minn, residents with a confirmed first stroke occurring between January 1, 1988, and December 31, 1989. One Rochester resident who had not had a stroke was matched to each person with stroke. Persons with and without stroke were followed up in provider-linked medical records and NH files from baseline (i.e., date of stroke) through December 31, 1994, for evidence of NH use. This study characterized the NH activity of those individuals with any NH activity after baseline (58 persons with major stroke, 36 persons with minor stroke, and 63 persons without stroke) as to NH case mix at first assessment, number of NH days, and per diem Medicaid reimbursement.

RESULTS

Characteristics at first NH assessment after baseline revealed that NH residents with major stroke were younger and more disabled and required more services than residents without stroke. Over the full period of follow-up, the mean number of NH days was similar for NH residents with major stroke and those without stroke, yet per diem Medicaid reimbursement was 11% higher for residents with major stroke compared with residents without stroke. Nursing home residents with minor stroke appeared similar to those without stroke with respect to time to admission, characteristics at first assessment, number of NH days, and per diem Medicaid reimbursement.

CONCLUSION

Lower incidence and severity of stroke may contribute to lower care needs and per diem cost, but no fewer NH days.

Referral to autopsy: effect of antemortem cardiovascular disease: a population-based study in Olmsted County, Minnesota

PURPOSE

Autopsy studies can provide insight into disease trends and their determinants, including data on the prevalence of atherosclerosis. However, such studies are subject to autopsy bias, which limits their generalizability to the source population. The impact of this bias on autopsy based estimates of time trends in heart disease prevalence is unknown. To report on the trends over time in autopsy rates in Olmsted County, MN, to examine the association between clinical diagnoses of cardiovascular diseases (CVDs) and referral to autopsy and how this association may have changed over time.

METHODS

We examined the trends in autopsy rates between 1979 and 1994 in Olmsted County, and the association between antemortem characteristics including cardiovascular diagnoses and autopsy referral.

RESULTS

From 1979 to 1994, a total of 9110 residents died in Olmsted County. The average annual autopsy rate was 30%. Autopsy rates declined from 36% in 1979 to 23% in 1994, corresponding to an average decline of 0.6%/year (p < 0.01). Referral to autopsy was positively associated with younger age, male sex, in-hospital place of death, antemortem diagnoses of myocardial infarction (MI) or peripheral vascular disease (PVD), and earlier calendar period. There was no evidence of an interaction between calendar period and any of these predictor variables. Antemortem diagnosis of heart failure was associated with a decrease in the odds of referral to autopsy over time as compared to persons without such diagnosis.

CONCLUSIONS

In Olmsted County, autopsy rates, although declining over time, have remained on average approximately 30%. Antemortem diagnoses of MI or PVD are associated with autopsy referral but this association did not change over time. While the greater decline overtime in the use of autopsy observed among decedents with an antemortem diagnosis of congestive heart failure (CHF) deserves further studies, the present findings reduce the concern for bias of time trends in the prevalence of atherosclerosis by changes in the clinical characteristics of decedents referred to autopsy.

Left atrial volume: important risk marker of incident atrial fibrillation in 1655 older men and women

OBJECTIVE

To evaluate the contribution of left atrial (LA) volume in predicting atrial fibrillation (AF).

PATIENTS AND METHODS

In this retrospective cohort study, a random sample of 2200 adults was identified from all Olmsted County, Minnesota, residents who had undergone transthoracic echocardiographic assessment between 1990 and 1998 and were 65 years of age or older at the time of examination, were in sinus rhythm, and had no history of AF or other atrial arrhythmias, stroke, pacemaker, congenital heart disease, or valve surgery. The LA volume was measured off-line by using a biplane area-length method. Clinical characteristics and the outcome event of incident AF were determined by retrospective review of medical records. Echocardiographic data were retrieved from the laboratory database. From this cohort, 1655 patients in whom LA size data were available were followed from baseline echocardiogram until development of AF or death. The clinical and echocardiographic associations of AF, especially with respect to the role of LA volume in predicting AF, were determined.

RESULTS

A total of 666 men and 989 women, mean +/- SD age of 75.2 +/- 7.3 years (range, 65-105 years), were followed for a mean +/- SD of 3.97 +/- 2.75 years (range, < 1.00-10.78 years); 189 (11.4%) developed AF. Cox model 5-year cumulative risks of AF by quartiles of LA volume were 3%, 12%, 15%, and 26%, respectively. With Cox proportional hazards multivariate models, logarithmic LA volume was an independent predictor of AF, incremental to clinical risk factors. After adjusting for age, sex, valvular heart disease, and hypertension, a 30% larger LA volume was associated with a 43% greater risk of AF, incremental to history of congestive heart failure (hazard ratio [HR], 1.887; 95% confidence interval [CI], 1.230-2.895; P = .004), myocardial infarction (HR, 1.751; 95% CI, 1.189-2.577; P = .004), and diabetes (HR, 1.734; 95% CI, 1.066-2.819; P = .03). Left atrial volume remained incremental to combined clinical risk factors and M-mode LA dimension for prediction of AF (P < .001).

CONCLUSION

This study showed that a larger LA volume was associated with a higher risk of AF in older patients. The predictive value of LA volume was incremental to that of clinical risk profile and conventional M-mode LA dimension.

Use and costs of medical care for children and adolescents with and without attention-deficit/hyperactivity disorder

CONTEXT

A shortage of data exists on medical care use by persons with attention-deficit/hyperactivity disorder (ADHD).

OBJECTIVE

To compare medical care use and costs among persons with and without ADHD.

DESIGN AND SETTING

Population-based cohort study conducted in Rochester, Minn.

SUBJECTS

All children born in 1976-1982 were followed up through 1995, using school and medical records to identify those with ADHD. The 4880 birth cohort members (mean age, 7. 3 years) still residing in Rochester in 1987 were followed up in medical facility-linked billing databases until death, emigration, or December 31, 1995.

MAIN OUTCOME MEASURES

Clinical diagnoses, likelihood and frequency of inpatient and outpatient hospitalizations, emergency department (ED) visits, and total medical costs (including ambulatory care), compared among individuals with and without ADHD.

RESULTS

Among the 4119 birth cohort members who remained in the area through 1995 (mean age, 15.3 years), 7.5% (n = 309) had met criteria for ADHD. Compared with persons without ADHD, those with ADHD were more likely to have diagnoses in multiple categories, including major injuries (59% vs 49%; P<.001) and asthma (22% vs 13%; P<.001). The proportion with any hospital inpatient, hospital outpatient, or ED admission was higher for persons with ADHD vs those without ADHD (26% vs 18% [P<. 001], 41% vs 33% [P =.006], and 81% vs 74% [P =.005], respectively). The 9-year median costs for persons with ADHD compared with those without ADHD were more than double ($4306 vs $1944; P<.001), even for the subset with no hospital or ED admissions (eg, median 1987 costs, $128 vs $65; P<.001). The differences between individuals with and without ADHD were similar for males and females and across all age groups.

CONCLUSION

In our cohort, compared with persons without ADHD, those with ADHD exhibited substantially greater use of medical care in multiple care delivery settings.

Trends in persistent proteinuria in adult-onset diabetes: a population-based study

OBJECTIVE

This study investigates temporal trends in the prevalence and incidence of persistent proteinuria among people with adult-onset diabetes (age > or =40 years).

RESEARCH DESIGN AND METHODS

The complete community-based medical records of all Rochester, Minnesota, residents with a diagnosis of diabetes or diabetes-like condition from 1945 through 1989 were reviewed to determine whether they met National Diabetes Data Group (NDDG) criteria. All confirmed diabetes cases residing in Rochester on 1 January 1970 (n = 446), 1980 (n = 647), and/or 1990 (n = 940) were identified. The medical records of these prevalence cases were reviewed from the time of the first laboratory urinalysis value to the last visit, death, or 1 April 1992 (whichever came first) for evidence of persistent proteinuria (two consecutive urinalyses positive for protein, with no subsequent negative values). Similarly, the medical records of all 1970-1989 diabetes incidence cases (n = 1,252) were reviewed to investigate temporal changes in 1) the likelihood of having persistent proteinuria before the date NDDG criteria was met, i.e., baseline; 2) the risk of persistent proteinuria after baseline; and 3) the relative risk of mortality associated with persistent proteinuria.

RESULTS

The proportion of diabetes prevalence cases with persistent proteinuria on or before the prevalence date declined from 20% in 1970 to 11% in 1980 and 8% in 1990. Among the 1970-1989 diabetes incidence cases, 77 (6%) had persistent proteinuria on or before baseline; the adjusted odds declined by 50% with each 10-year increase in baseline calendar year (P<0.001). Among individuals free of persistent proteinuria at baseline, 136 subsequently developed persistent proteinuria; the estimated 20-year cumulative incidence was 41% (95% CI 31-59); the adjusted risk did not differ as a function of baseline calendar year. Survival of individuals with persistent proteinuria relative to those without was reduced but did not differ by baseline calendar year.

CONCLUSIONS

The prevalence of persistent proteinuria among people with adult-onset diabetes in Rochester, Minnesota, declined 60% between 1970 and 1990. The decline appears because of a decrease in the proportion of diabetes incidence cases with persistent proteinuria before baseline rather than secular declines in the risk of persistent proteinuria after baseline or secular increases in the risk of mortality associated with persistent proteinuria. Similarity over time in age and fasting glucose at baseline, and at prevalence dates, is evidence that earlier detection of diabetes is not the sole explanation for the decline.

The role of depression in the association between self-rated physical health and clinically defined illness

We enrolled 543 elderly participants of a managed care organization in a cross-sectional study to test whether the association between self-rated physical health and clinically defined illness differs for persons who are not depressed compared with persons with minor or serious depression. Depression was measured with the Diagnostic Interview Schedule (DIS). Clinically defined illness was measured with the Chronic Disease Score (CDS), a pharmacy-based measure. Additional variables included age, sex, and self-reported pain and physical function. Self-rated physical health was associated with both minor and serious depression, independent of clinically defined illness; minor depression was no longer significant when self-reported pain and physical function were added to the model. A significant negative correlation between self-rated physical health and clinically defined illness was observed for minor and no depression, but no correlation was seen for serious depression. These results confirm the association between depression and self-rated physical health and emphasize that, for persons with serious depression, self-rated health provides a less accurate picture of clinically defined illness at both ends of the spectrum. Also, a diagnosis of minor depression should not forestall investigation of inconsistencies between patient report and clinical evidence.

Use of nursing home after stroke and dependence on stroke severity: a population-based analysis

BACKGROUND AND PURPOSE

There are few population-based data available regarding nursing home use after stroke. This study clarifies the use of a nursing home after stroke, as well as its dependence on stroke severity, in a defined population.

METHODS

All first stroke events among residents of Rochester, Minn, during 1987-1989 were ascertained, subtyped, and assigned Rankin disability scores (RS) before the event, at maximal deficit, and at specified intervals after stroke. Persons were followed from the date of stroke event to death, emigration from Rochester, or December 31, 1994, in complete community-based medical records and Minnesota Case Mix Review Program data tapes to determine nursing home residency before stroke and at 90 days and 1 year after stroke, proportion of survival days in a nursing home, and cumulative risk of admission to a nursing home.

RESULTS

There were 251 cases of first cerebral infarction, 24 intracerebral hemorrhages, and 15 subarachnoid hemorrhages among residents of Rochester during 1987-1989. The maximal deficit RS was 1 or 2 for 62 (25%), RS 3 for 72 (29%), and RS 4 or 5 for 117 (47%) of the cerebral infarct patients. Among patients surviving to 90 days or 1 year after cerebral infarction, 25% were in nursing home at 90 days and 22% at 1 year, respectively. Within these maximal deficit RS categories, the percentages of follow-up time spent in a nursing home during the first post-cerebral infarction year are as follows: RS 1 to 2, 4%; RS 3, 10%; and RS 4 to 5, 54%. Multivariate logistic regression revealed that increasing age and RS 4 to 5 at maximal deficit were independent predictors (P<0.0001) of nursing home residency at 90 days and 1 year after stroke, whereas stroke type was not an independent predictor. At 1 year after cerebral infarction, the Kaplan-Meier estimates of proportion of people with at least 1 nursing home admission were 11% for RS 1 to 2, 22% for RS 3, and 68% for RS 4 to 5.

CONCLUSIONS

This study provides unique population-based data regarding the short- and long-term use of a nursing home after stroke and its dependence on stroke severity. More than 50% of people with a severe cerebral infarction are in a nursing home 90 days and 1 year after the stroke, and by 1 year, nearly 70% will have required some nursing home stay. Age and stroke severity are independent predictors of nursing home residency after stroke.

Effects of changing diagnostic criteria on the risk of developing diabetes

OBJECTIVE

The American Diabetes Association (ADA) has recommended that the fasting plasma glucose (FPG) level used to diagnose diabetes be changed from 7.8 mmol/l (the level recommended by the National Diabetes Data Group [NDDG] in 1979) to 7.0 mmol/l. We examined the impact of this change on rates of progression to overt diabetes from different levels of FPG.

RESEARCH DESIGN AND METHODS

Using the laboratory database of Mayo Clinic, we assembled a cohort of 8,098 nondiabetic Olmsted County residents 40 years of age or older on 1 July 1983. Subjects were followed for a median of 9 years.

RESULTS

Among 7,567 individuals with follow-up FPG data, 778 (10.3%) progressed to ADA diabetes and 513 (6.8%; P < 0.0001) progressed to NDDG diabetes. The risk of developing ADA diabetes was 7, 19, and 39% for individuals with initial FPG values in the ranges of <5.6, 5.6-6.0, and 6.1-6.9 mmol/l, respectively. For progression to NDDG diabetes, the respective risks were 3, 11, and 25%. A clear gradient of risk was observed within the "normal" range of FPG (<5.6 mmol/l). Among the 793 individuals who developed ADA diabetes, 222 (29%) developed NDDG diabetes simultaneously and 291 (37%) developed NDDG diabetes later. In all FPG subgroups, progression to ADA diabetes occurred approximately 7 years sooner than progression to NDDG diabetes.

CONCLUSIONS

The baseline level of FPG is a major predictor of an individual's risk of developing diabetes. The proposed change in the diagnostic criteria for diabetes will lead to earlier diagnosis among individuals who are destined to develop the disease.

Stroke-attributable nursing home use: a population-based study

OBJECTIVE

To estimate 1) among patients with stroke, nursing home use attributable to stroke, and 2) the savings in nursing home use, assuming strokes were prevented.

METHODS

All confirmed cases of first stroke among Rochester, Minnesota, residents from 1987 through 1989 (n = 290) and one nonstroke control of same gender and similar age for each patient were followed up in provider-linked medical records and State of Minnesota nursing home files until emigration, death, or December 31, 1994. Data included disability and place of residence at baseline (i.e., date of stroke for each patient and their corresponding control), length of follow-up, cumulative incidence of nursing home admission, proportion of follow-up spent in a nursing home, and number of nursing home days.

RESULTS

Before baseline, patients and controls were similar in the level of disability (mean Rankin = 1.7 for patients and 1.6 for controls) and the proportion in a nursing home (11% for both groups). Among those not in the nursing home at baseline, 5-year cumulative incidence of first admission was 48% for cases versus 20% for controls. Survival was significantly shorter for cases than for controls; the proportion of follow-up spent in the nursing home was 20% for cases versus 11% for controls. When controlling for survival, cases experienced an average of 110 (95% CI, 63 to 156) more nursing home days per person than controls in the first five years. When nursing home use during differential survival was included, the difference in nursing home days between cases and controls was no longer significant (p = 0.16).

CONCLUSIONS

Stroke prevention would result in fewer cases admitted to the nursing home, older age at first admission, and a smaller proportion of remaining life spent in the nursing home, but stroke prevention would not result in fewer nursing home days.

Relative contributions of incidence and survival to increasing prevalence of adult-onset diabetes mellitus: a population-based study

This population-based retrospective study investigates temporal trends in adult-onset diabetes mellitus prevalence, incidence, and survival. The complete community-based medical records, including laboratory results, of all Rochester, Minnesota, residents with a clinical diagnosis of diabetes or diabetes-like condition were reviewed to identify incidence cases aged 30 years or more from 1945 to 1989 (n = 1,847) and prevalence cases aged 45 years or more on January 1, 1970 (n = 465), January 1, 1980 (n = 689), or January 1, 1990 (n = 973). Glucose values and case definitions were standardized throughout. Observed 10-year survival for 1970 and 1980 prevalence cases was compared with that expected for Minnesota white populations in 1970 and 1980, respectively. Age-adjusted prevalence rose 65% for men and 37% for women between 1970 and 1990. There were marked differences among prevalence groups in treatment type, the proportion diagnosed using glucose tolerance tests, and the proportion categorized as obese. Relative survival for 1980 prevalence cases was not greater than that for 1970 prevalence cases. Age-adjusted incidence rates rose 47% for men and 26% for women between 1960 and 1965 and 1985 and 1989. These findings emphasize the need for heightened surveillance and intervention to reduce the burden of illness from adult-onset diabetes mellitus in the population.

Risk of dementia among persons with diabetes mellitus: a population-based cohort study

It is unclear whether persons with diabetes are at increased risk for dementia, including Alzheimer's disease. Existing studies are limited by small sample size, selection bias, and case-control designs. This population-based historical cohort study provides estimates of the risk of dementia and Alzheimer's disease associated with adult onset diabetes mellitus (AODM). The sample included all persons with AODM residing in Rochester, Minnesota, on January 1, 1970, plus all persons diagnosed in Rochester or who moved to Rochester with the diagnosis between January 1, 1970, and December 31, 1984. Individuals were followed through review of their complete medical records from AODM diagnosis until dementia onset, emigration, death, or January 1, 1985. Standardized morbidity ratios for dementia and Alzheimer's disease were calculated, using an expected incidence based on age- and sex-specific rates for the Rochester population. Poisson regression was used to estimate risks for persons with AODM relative to those without. Of the 1,455 cases of AODM followed for 9,981 person-years, 101 developed dementia, including 77 who met criteria for Alzheimer's disease. Persons with AODM exhibited significantly increased risk of all dementia (Poisson regression relative risk (RR) = 1.66, 95% confidence interval (CI) 1.34-2.05). Risk of Alzheimer's disease was also elevated (for men, R = 2.27, 95% CI 1.55-3.31; for women, RR = 1.37, 95% CI 0.94-2.01). These findings emphasize the importance of AODM prevention and prompt additional investigation of the relation between AODM and dementia.

Utilization of acute care services in the year before and after first stroke: A population-based study

There is a need for accurate population-based data on the utilization of medical resources after stroke. The present study used the Rochester Stroke Registry to identify all Rochester, Minnesota residents with confirmed first stroke (hospitalized and nonhospitalized) during the period of 1987 to 1989 (n=292). Events were categorized by type of stroke and assigned Rankin severity. Inpatient and outpatient acute care activity for the 12 months before and after stroke for each individual were obtained from billing tapes provided by Mayo Clinic, Olmstead Medical Group, and affiliated hospitals. These providers account for >95% of acute care received by Rochester residents. The results showed that despite high poststroke mortality, total charges in the year after stroke were 3.4 times those for the previous year. Although greater than 50% of utilization in the year poststroke occurred within the first 30 days, mean monthly charges for acute care remained significantly above prestroke levels for up to 5 months after the event. Poststroke charges per person-day of follow-up were significantly higher for individuals who were hospitalized for the event, who had subarachnoid hemorrhage, whose stroke occurred after admission to the hospital for another reason, and who died within 7 days. Significantly lower poststroke charges were evident for persons with mild cerebral infarctions and persons whose stroke occurred in a nursing home. Neither prestroke utilization, age category, nor sex were predictive of poststroke charges. The unique population-based data presented here have important implications for efforts toward stroke prevention, intervention, and cost containment.

Insulin therapy for diabetic ketoacidosis. Bolus insulin injection versus continuous insulin infusion

OBJECTIVE

Despite widespread acceptance of continuous insulin infusion (CII) over bolus insulin injection (BII) for treatment of diabetic ketoacidosis (DKA), there are no population-based studies demonstrating whether CII has resulted in lower morbidity and mortality.

RESEARCH DESIGN AND METHODS

We addressed this issue using a provider-linked database and retrospectively reviewing the complete medical records of all incidence cases of diabetes among Rochester, Minnesota, residents from 1950 to 1989 with a discharge diagnosis of DKA. This population-based study describes the consequences of the widespread change in treatment modality outside the confines of a controlled clinical trial.

RESULTS

Among the diabetes incident cohort, there were 59 subjects with confirmed first episodes of DKA during 1950-1992; 29 of 30 subjects treated with BII occurred before 1970. All 29 CII cases occurred between 1976 and 1992. Sex, etiology, diabetes duration, and age at DKA were similar for the two groups. The proportion of obese individuals (BII = 2/28, CII = 8/21; P = 0.01) differed between groups. The CII group exhibited higher glucose values (BII = 24.9 +/- 8.5 mmol/l, CII = 37.1 +/- 15.1 mmol/l; P = 0.002) and lower bicarbonate values (BII = 7.7 +/- 3.0 nmol/l, CII = 6.2 +/- 2.9 nmol/l; P = 0.04) upon admission. The mean quantity of insulin administered was higher in the BII group than in the CII group (179 +/- 140 and 99 +/- 70 U, P < 0.006). The outcome of hypoglycemia occurred more frequently in the BII group than in the CII group (BII = 8/30, CII = 1/29; P = 0.03). The proportion with hypokalemia, neurological deficit, myocardial arrhythmia, or mortality did not differ significantly between groups.

CONCLUSIONS

Our findings suggest the introduction of CII was accompanied by a decreased incidence of hypoglycemia.

Accuracy of hospital discharge abstracts for identifying stroke

BACKGROUND AND PURPOSE

Much of the available data on stroke occurrence, service use, and cost of care originated with hospital discharge abstracts. This article uses the unique resources of the Rochester Epidemiology Project to estimate the sensitivity and positive predictive value of hospital discharge abstracts for incident stroke.

METHODS

The Rochester Stroke Registry was used to identify all confirmed first strokes (hospitalized and nonhospitalized) among Rochester residents for 1970, 1980, 1984, and 1989 (n = 364). The sensitivity of discharge abstracts was estimated by following these individuals for 12 months after stroke to determine the proportion assigned a discharge diagnosis of cerebrovascular disease (International Classification of Diseases [ICD] codes 430 through 438.9). The positive predictive value of discharge abstracts was assessed by identifying all hospitalizations of Rochester residents with an ICD code of 430-438.9 in 1970, 1980, and 1989 (n = 377). Events were categorized as incident stroke, recurrent stroke, stroke sequelae, or nonstroke after review of the complete community-based medical record by a neurologist.

RESULTS

Only 86% (n = 313) of all first-stroke patients in 1970, 1980, 1984, and 1989 were hospitalized. Of hospitalized patients, only 76% were assigned a principal discharge diagnosis code of 430-438.9. Fatal strokes and those occurring during a hospitalization were less likely to be identified. Among all hospitalizations of Rochester residents in 1970, 1980, and 1989, there were 377 with a principal diagnosis code of 430-438.9. Less than half (n = 177) were determined by the neurologist to be incident stroke; only 60% (n = 225) were either incident or recurrent stroke. Comparison of alternative approaches showed the validity of discharge abstracts was enhanced by increasing the number of diagnoses and excluding codes with poor positive predictive value.

CONCLUSIONS

This study provides previously unavailable estimates of the sensitivity of stroke-coded hospitalizations for a US community. A model for improving the sensitivity and positive predictive value of discharge abstracts is presented.

Contribution of a measure of disease complexity (COMPLEX) to prediction of outcome and charges among hospitalized patients

Attention has been focused on the need to adjust hospital reimbursement and outcomes of hospital care for level of illness. Extant measures of disease severity, however, fail to consider the contribution of disease complexity. We developed an easily retrievable measure of disease complexity (COMPLEX) by modifying an existing severity system, computerized Disease Staging. The contribution of COMPLEX (the number of body systems affected with a Disease Staging score of 2 or more) to the prediction of outcome was assessed in two studies: (1) a population-based analysis of readmission and mortality after hospitalization and (2) an analysis of hospital charges among patients who were in an intensive-care unit. The amount of variation in mortality explained by factors included in the Health Care Financing Administration model was significantly improved when COMPLEX was added to the model (adjusted odds ratio per body system, 1.83; 95% confidence interval, 1.61 to 2.08). A significant association was also observed between COMPLEX score and hospital readmission after adjustment for age, sex, case-mix, and disease severity (adjusted odds ratio, 1.31; 95% confidence interval, 1.20 to 1.44). When COMPLEX was added to case-mix and disease severity in a model for predicting hospital charges, the percentage of variation in hospital charges explained by the model increased from 25% to 38%. These findings demonstrate the important contribution of disease complexity to the analysis of outcome of medical care and utilization of resources. Outcome or reimbursement models that do not incorporate disease complexity may negatively affect institutions with a high proportion of patients who have complex conditions.

The Olmsted County Benchmark Project: primary study findings and potential implications for corporate America

Since 1965, expenditures for medical care in the United States have increased 10-fold. As a result, corporate outlays for health benefits have skyrocketed. Employers have instituted various cost-containment measures based in part on reports of wide variations in rates of utilization and the assumption that unnecessary or inappropriate utilization of medical care contributes to increasing costs. Frequently, however, employers lack adequate means for identifying sources of variation or for evaluating its appropriateness. In this article, we report on a project in which hospital utilization among several US corporate populations was compared with that for a geographically defined benchmark population to assist employers in the assessment of their rates of utilization and expenditures and to identify specific areas that merit further investigation. Our findings illuminate the difficulties in constructing valid rates from medical-care claims data and emphasize potential biases due to problems of comparability between populations. We also address the potential value of such comparison for helping corporations identify areas in which cost-containment efforts may be most effective and yet not jeopardize the quality of medical care.

Trends in elderly hospitalization and readmission rates for a geographically defined population: pre- and post-prospective payment

To address the paucity of patient-level data regarding the effectiveness of Medicare's prospective payment system (PPS), we conducted a population-based study of inpatient hospitalizations among individually identified elderly residents of Olmsted County, Minnesota, 1970-1987. A 4.3% increase in total days of care/1000 population from 2,652/1,000 in 1970 to 2,766/1,000 in 1980 was followed by a 9.8% decline from 1980 to 1987 (2,495/1,000). The decline was due primarily to a 13.4% decrease in mean length stay (9.7 days in 1980 to 8.4 days in 1987). The number of hospitalizations/1,000 Olmsted County elderly in 1980 was already below 1987 U.S. figures and did not exhibit the decline evidenced nationally between 1980 and 1987. A 4.6% decline in the proportion of county residents age 65-74 years who were hospitalized (174/1,000 in 1980 to 166/1,000 in 1987) was offset by an 8.3% increase for persons age greater than or equal to 75 (252/1,000 to 273/1,000) and by a 5.7% increase in the number of hospitalizations per individual hospitalized for persons age 65-74 years (1.34 to 1.42). Using a time-dependent Cox model, which adjusted for differences in patients characteristics between years, there was a significantly higher risk of readmission within 14 days in 1987 vs 1980 (hazard ratio (HR) = 1.33, 95% confidence interval (CI) = 1.05-1.70). The difference between years was no longer evident at 30 or 60 days (HR = 0.84, 95% CI = 0.63-1.11 between 15 and 30 days; HR = 1.12, 95% CI = 0.84-1.49 between 31 and 60 days). This study suggests that initial effects of PPS on utilization may be temporary and that more research is needed to appreciate the impact of cost-containment on patient outcome.