Biomedical subjects

C S Crowson

Publications and source records attributed to C S Crowson.

33 records · Page 2Linked to original sources

PubMed1999

Primary hyperparathyroidism and the risk of fracture: a population-based study.

While severe primary hyperparathyroidism (HPT) is clearly associated with osteitis fibrosa cystica, it remains uncertain whether mild, asymptomatic primary HPT adversely affects the skeleton. Thus, we assessed the incidence of age-related fractures in a large, population-based inception cohort of 407 cases of primary HPT (93 men and 314 women) recognized during the 28-year period, 1965-1992. Fracture risk was assessed by comparing new fractures at each site to the number expected from gender- and age-specific fracture incidence rates for the general population (standardized incidence ratios, SIRs). These community patients with primary HPT mostly had mild disease (mean +/- SD serum calcium, 10.9 +/- 0.6 mg/dl). Altogether, 471 fractures occurred during 5766 person-years of follow-up. Overall fracture risk was significantly increased in these patients (SIR 1.3, 95% confidence interval [CI] 1.1-1.5). Primary HPT was associated with an increased risk of vertebral (SIR 3.2, 95% CI 2.5-4.0), distal forearm (SIR 2.2, 95% CI 1.6-2.9), rib (SIR 2.7, 95% CI 2.1-3.5), and pelvic fractures (SIR 2.1, 95% CI 1. 1-3.5). The risk of proximal femur fractures was only marginally increased (SIR 1.4, 95% CI 1.0-2.0). By univariate analysis, increasing age and female gender were significant predictors of fracture risk, although higher serum calcium levels were also associated with increased fracture risk, and parathyroid surgery may have had a protective effect. By multivariate analysis, however, only age (relative hazard [RH] per 10-year increase, 1.6, 95% CI 1. 4-1.9) and female gender (RH 2.3, 95% CI 1.2-4.1) remained significant independent predictors of fracture risk. Thus, primary HPT among unselected patients in the community is associated with a significant increase in the risk of vertebral, Colles', rib, and pelvic fractures. These data have important implications for the current trend to recommend nonsurgical management for patients with mild primary HPT.

Adolescent↗

PubMed1999

Long-term fracture risk among women with anorexia nervosa: a population-based cohort study.

OBJECTIVE: To determine if fractures represent an important problem for women with anorexia nervosa who may fail to achieve peak bone mass and may experience premature bone loss from decreased estrogen levels. PATIENTS AND METHODS: In this population-based retrospective cohort study, we identified 208 Rochester, Minn, residents that were first diagnosed as having anorexia nervosa between 1935 and 1989, whose subsequent fractures were documented in contemporary medical records and compared with expected numbers of fractures (standardized incidence ratios [SIRs]). RESULTS: Subjects were followed up for 2689 person-years during which time 45 patients suffered 88 fractures. Fracture risk was increased among the 193 women (SIR, 2.9; 95% confidence interval, 2.0-3.9) as well as the 15 men (SIR, 3.4; 95% confidence interval, 1.1-7.9). The cumulative incidence of any fracture at 40 years after the diagnosis of anorexia nervosa was 57%. Fractures of the hip, spine, and forearm were late complications, occurring on average 38, 25, and 24 years, respectively, after diagnosis. CONCLUSION: Young women with anorexia nervosa are at increased risk of fractures later in life. Greater attention should be paid to the skeletal health of these individuals.

Adolescent↗

PubMed1999

Modeling the lifetime costs of rheumatoid arthritis.

OBJECTIVE: To develop an analytical approach for estimating the lifetime costs of rheumatoid arthritis (RA) using existing population based cross sectional data, and to use this estimate to describe the potential cost-effectiveness of bone marrow transplantation for RA. METHODS: Estimates of arthritis related costs (direct, indirect, and nonmedical) and mortality were obtained from previously assembled population based cohorts. A mathematical model was designed defining 25 hypothetical ratios (RA/NA) representing the proportionate excess cost of RA each year for the 25 years following a diagnosis of RA. Using age and sex-specific cost estimates, we then simulated a vector of 25 ratios 1000 times. Each age and sex-specific randomly generated variable was converted to an estimated dollar amount (in 1995 dollars US) of excess cost attributable to RA. All dollar amounts were discounted by 3% per year. Finally, each vector of 25 discounted dollar amounts was summed to yield an estimate of the total excess medical costs in 1995 dollars for the first 25 years of a person's lifetime following a diagnosis of RA. Because not every one of these hypothetical individuals would be expected to live all 25 years, we used the standardized mortality ratio for an individual with RA (from our inception cohort) and multiplied it by the age-specific 1990 mortality rates for Minnesota whites to estimate how many of the 1000 randomly generated hypothetical individuals could be expected to die during each of the 25 years. For these, the summation of estimated cost was truncated at the death year. This process yielded, for each age and sex, a sample of 1000 sums of 25 (or fewer) excess costs all in terms of 1995 dollars that correspond to the excess cost during the first 25 years after an RA diagnosis, adjusted for differential survival among patients with RA compared to nonarthritic controls. The distribution of these sums thus represented a distribution of the 1995 dollars that could be saved if RA could be "cured" soon after incidence. RESULTS: Our simulation analyses indicated that the median lifetime incremental costs of RA range roughly from ,$61,000 to $ 122,000. Incremental costs were higher for younger individuals compared to older individuals and were consistent over all percentiles and age groups. No systematic relationship between the incremental costs of females with RA compared to males was identified. CONCLUSION: These data suggest that interventions such as autologous bone marrow transplantation, which has recently been estimated to cost roughly $60,000, may be cost saving if they eliminate the downstream incremental costs of RA.

Adult↗

PubMed1999

Comorbidity in arthritis.

OBJECTIVE: To describe the relative frequency of selected comorbidities in 2 population based prevalence cohorts of patients with rheumatoid arthritis (RA) and osteoarthritis (OA) compared to age and sex matched community controls. METHODS: Using the population based data resources of the Rochester Epidemiology Project, we assembled 3 prevalence cohorts of all residents of Olmsted County, Minnesota, with RA (1987 American College of Rheumatology criteria) and age and sex matched controls without arthritis on January 1, 1965, January 1, 1975, and January 1, 1985. Cases and controls were followed longitudinally through their complete (inpatient and outpatient) medical records beginning 10 years prior to the prevalence (or index) date until death, migration from the county, or January 1, 1995. Comorbidity was assessed yearly using the Charlson Comorbidity Index and the Index of Co-existent Diseases (ICED). Descriptive statistics were used to illustrate the baseline characteristics of the study population and the frequency of individual comorbidities in each of the 3 groups over the followup period. Cox proportional hazards modeling was used to assess the risk for each individual comorbidity among patients with arthritis compared to controls and to identify significant predictors of an increase in comorbidity level over time. RESULTS: Our study population included 450 RA, 441 OA, and 891 control subjects. The age and sex distributions of cases and their controls were similar. Over the followup period, patients with RA had a higher likelihood of developing congestive heart failure, chronic pulmonary disease, dementia, and peptic ulcer disease, while cases with OA had a significantly higher risk of developing peptic ulcer disease and renal disease. Among patients with either RA or OA, age, male sex, and baseline comorbidity were significant predictors of a rise in comorbidity. The presence of RA was a highly significant predictor of a rise in comorbidity from one year to the next, even after controlling for the effects of age, sex, and baseline comorbidity (p = 0.0004 for the Charlson and p = 0.006 for the ICED). CONCLUSION: These data indicate that the burden of illness among people with arthritis is higher than for nonarthritics and that this burden appears to be increasing over time, particularly in RA. These results suggest that specialized chronic disease care will be increasingly important for the future health care needs of people with RA.

Arthritis, Rheumatoid↗

PubMed1999

Mortality in rheumatoid arthritis: have we made an impact in 4 decades?

OBJECTIVE: To evaluate trends in survival among patients with rheumatoid arthritis (RA) over the past 4 decades. METHODS: Three population based prevalence cohorts of all Rochester, Minnesota, residents age > or =35 years with RA (1987 American College of Rheumatology criteria) on January 1, 1965, January 1, 1975, and January 1, 1985; and an incidence cohort of all new cases of RA occurring in the same population between January 1, 1955 and January 1, 1985, were followed longitudinally through their entire medical records (including all inpatient and outpatient care by any provider) until death or migration from the county. Mortality was described using the Kaplan-Meier method and the influence of age, sex, rheumatoid factor (RF) positivity, and comorbidity (using the Charlson Comorbidity Index) on mortality was analyzed using Cox proportional hazards models. RESULTS: Mortality was statistically significantly worse than expected for each of the cohorts (overall p<0.0001). A trend toward increased mortality in the 1975 and 1985 prevalence cohorts compared to the 1965 prevalence cohort was present, even after adjusting for significant predictors of mortality (age, RF positivity, and comorbidity). Survival for the general population of Rochester residents of similar age and sex improved in 1975 compared to 1965, and in 1985 compared to 1975. CONCLUSION: The excess mortality associated with RA has not changed in 4 decades. Moreover, people with RA have not enjoyed the same improvements in survival experienced by their non-RA peers. More attention should be paid to mortality as an outcome measure in RA.

Adult↗

PubMed1998

Long-term trends in the incidence of distal forearm fractures.

In this population-based descriptive study covering the 50-year period, 1945-94, there was a statistically significant increase in distal forearm fractures due to severe trauma in both women and men (p < 0.001) but no secular increase in fractures due to moderate trauma (approximately osteoporosis). Since fractures attributed to severe trauma comprised a greater proportion of the total in men (52%) than women (21%), an overall doubling of age-adjusted forearm fracture incidence in men between 1945 and 1994 was statistically significant (p < 0.001), but the 7% increase in age-adjusted rates among women was not (p = 0.90). While the epidemiological pattern of distal forearm fracture incidence in Rochester was similar to that seen elsewhere, the overall incidence rate of 287.4 per 100,000 person-years (95% CI 267.7-307.1) in 1985-94 was less than current rates in Sweden, presumably because the great increase in distal forearm fracture incidence seen, for example, in Malmö between 1953-57 and 1980-81 was not observed in Rochester. The trends in distal forearm fracture rates in Rochester men and women over the past 50 years are broadly consistent with trends in hip fracture incidence in this community over the same time span.

Adult↗

PubMed1998

Fracture risk among patients with urolithiasis: a population-based cohort study.

In a population-based retrospective cohort study, 624 Rochester, Minnesota residents with an initial symptomatic episode of urolithiasis in 1950 to 1974 were followed for 11,909 person-years for subsequent age-related fractures. During this period of observation, the number of patients with a first vertebral fracture was over four times the number expected on the basis of vertebral fracture incidence rates in the general population of Rochester [standardized morbidity ratio (SMR), 4.3; 95% confidence interval, 3.4 to 5.3]. The risk of vertebral fracture was elevated among men as well as women, and was associated with increasing age and with the use of corticosteroids for more than six months. However, vertebral fracture risk was increased nearly fourfold (SMR 3.9; 95% confidence interval, 3.0 to 4.9) among the urolithiasis patients without such exposure, which suggests that corticosteroids do not completely account for the association with vertebral fractures. There was no increase in the risk of hip, pelvis, proximal humerus or distal forearm fractures in this cohort of patients, and their survival was not impaired. Additional studies are needed to define the pathophysiology of vertebral fractures among patients with urolithiasis.

Adolescent↗

PubMed1997

Indirect and nonmedical costs among people with rheumatoid arthritis and osteoarthritis compared with nonarthritic controls.

OBJECTIVE: Compared to rheumatoid arthritis (RA), osteoarthritis (OA) is considered much more benign and much less costly. We sought to describe the economic effects of RA and OA, in terms of the indirect and nonmedical expenditures, compared to nonarthritic controls. METHODS: Using our unique population based data resources, we developed a model for estimating and comparing disease specific costs among 2 randomly selected, community based samples of 200 patients each with RA and OA and a control group of 200 individuals from the same community who do not have arthritis. Data were collected using a pretested postal survey. Age and sex adjusted comparisons were conducted across the 3 groups, and predictors of cost and utilization were identified using logistic regression modeling. RESULTS: There were 123, 116, and 94 respondents among the RA, OA, and nonarthritis groups, respectively. The average age and the female-to-male ratios were higher in the OA and RA groups compared to the nonarthritis group. Patients with RA and OA required 3 times more days of care for their conditions compared to nonarthritics (p < 0.0001) and incurred significantly more expenditures for home or child care (p = 0.01) and other services (p = 0.001) (i.e., medical equipment, assistive devices, or home remodeling) compared to nonarthritics. In addition, patients with RA were significantly more likely to have lost their job or to have retired early due to their illness (p = 0.001); were the most likely to have reduced their work hours or stopped working entirely due to their illness (p = 0.003); and were 3 times more likely to have had a reduction in household family income than either individuals with OA or those without arthritis (p = 0.0001). Fifteen percent of respondents with RA were unable to get a job because of their illness, while 3% of respondents with OA and only 1% of nonarthritic respondents reported this experience (p = 0.001). Logistic regression analysis revealed that functional status and pain score, as well as the presence of either RA or OA, were significant predictors of cost and health services utilization. CONCLUSION: Disease specific indirect and nonmedical costs for OA are substantial and approach those for RA. This has important societal implications, given the high prevalence of OA.

Arthritis, Rheumatoid↗

PubMed1997

Direct medical costs unique to people with arthritis.

OBJECTIVE: We report the results of a population based analysis of all health services used and charges incurred over a one-year period among a community based cohort of persons with a diagnosis of arthritis [including both osteoarthritis (OA) and rheumatoid arthritis (RA)] compared to a similar cohort of individuals from the same community who have never had a diagnosis of arthritis (NA), to examine the attributable costs of this chronic condition. METHODS: The unique resources of the Rochester Epidemiology Project were used to assemble the arthritis prevalence cohorts and the population based control cohort. The Olmsted County Health Care Utilization and Expenditures Database was used to collect information on health services utilization and charges. RESULTS: The average direct medical charges for the RA, OA, and NA cohorts were $3,802.05, $2,654.51, and $1,387.83, respectively (age and sex adjusted, p < 0.0001 for both the RA vs NA and OA vs NA comparisons). The median charges for these 3 groups were $1,050.00, $663.55, and $232.04 for the RA, OA, and NA groups, respectively (age and sex adjusted p < 0.0001 for both the RA vs NA and OA vs NA comparisons). These analyses indicated that, compared to the NA cohort both the OA and the RA prevalence cohorts incurred statistically significantly more charges, not only for the musculoskeletal disease care, but also for the care of numerous other conditions including respiratory, cardiovascular, gastrointestinal, neurological, and psychiatric conditions; and for general medical care. Individuals with arthritis (both OA and RA) also incurred statistically significantly more charges for diagnostic and therapeutic procedures, in-hospital care, imaging studies, physician services, equipment, and laboratory studies. Use of prescription medications was statistically significantly more common in the RA and OA groups compared to NA (96.3, 96, and 83%, respectively; age and sex adjusted p = 0.006 for the OA vs NA comparison and p = 0.015 for RA vs NA). CONCLUSION: These results emphasize the importance of considering all health services utilization (rather than only disease specific use) when estimating the economic effect of a chronic illness such as arthritis.

Adult↗

PubMed1996

A mathematical model that improves the validity of osteoarthritis diagnoses obtained from a computerized diagnostic database.

We developed an algorithm, using recursive partitioning, that utilized information from a computerized, diagnostic database to predict the diagnosis of osteoarthritis as determined by medical record review. The complete (inpatient and outpatient) medical records for a random sample of 400 Olmsted County, Minnesota residents with a database diagnosis consistent with osteoarthritis were reviewed, and confirmation or rejection of the diagnosis was accomplished. Of the 387 patients in our sample, only 232 (a positive predictive value of 60%) fulfilled diagnostic criteria for osteoarthritis following medical record review. A classification tree was created that used information from the diagnostic database to partition the study population according to the proportion of individuals with a "true" diagnosis of osteoarthritis (based on medical record review). The receiver-operating characteristic curve generated from these data illustrated that the algorithm substantially improved the validity of the database diagnosis, yielding a positive predictive value of 89% and a negative predictive value of 70% (sensitivity of 75% and specificity of 86%) at a selected cutoff point. This model also provides the capability of selecting the cutoff point to favor either specificity or sensitivity. These data demonstrate that a mathematical model can substantially improve the validity of computerized diagnostic databases in osteoarthritis.

Adult↗

PubMed1996

Fracture risk following bilateral oophorectomy.

To assess fracture risk following bilateral oophorectomy, we conducted a population-based retrospective cohort study among the 463 Rochester, Minnesota women who underwent bilateral oophorectomy for benign ovarian conditions in 1950-1979. During 7220 person-years of observation, there appeared to be a modest increase in the risk of distal forearm fractures (standardized morbidity ratio [SMR] 1.4; 95% CI 1.0-2.0) and vertebral fractures (SMR 1.9; 95% CI 1.3-2.8) but not hip fractures (SMR] 1.1; 95% CI 0.6-1.9). Although our statistical power was quite limited, there was a suggestion that women who became estrogen deficient at a young age were at greater risk of fracture. However, the youngest women were more likely to be on estrogen replacement therapy, and for longer durations, so that the average age at the onset of estrogen deficiency in this population was 47 years.

Age Factors↗

PubMed1995

Costs of osteoarthritis: estimates from a geographically defined population.

Using the population based data resources of the Rochester Epidemiology Project and a postal survey, we estimated all costs (direct medical, indirect medical, and nonmedical) incurred among a population based prevalence cohort of individuals with osteoarthritis (OA) and a nonarthritic comparison cohort. Cost estimates were compared between the 2 groups adjusting for age and sex differences. Our results demonstrated that people with OA incur substantial incremental medical costs, not only for arthritis care, but also for the care of neurological, gastrointestinal, cardiac, and respiratory conditions compared to nonarthritics. These data also demonstrated important and statistically significantly higher levels of work disability among people with OA compared to their age and sex adjusted peers without arthritis from the same community.

Adult↗

PubMed1993

Competitive athletes: preinjury and postinjury mood state and self-esteem.

In a prospective study, we determined whether preinjury and postinjury differences existed in the mood state and self-esteem of competitive athletes. The influence of severity of injury, gender, level of participation in sports, and type of sport on these dependent variables was also measured. Among 238 male and 38 female athletes from hockey, basketball, baseball, and volleyball teams, 36 sustained 43 injuries. Significant postinjury increases were noted for depression (P < 0.0001) and anger (P = 0.0012), whereas vigor (P < 0.0001) was significantly less after injury. When the 36 injuries were classified, 27 were minor or moderate (nonparticipation in sports for only one or two weekly assessments), and 9 were severe (nonparticipation for three or more weekly assessments). When a stepwise multiple regression equation was used to predict the scores for postinjury depression, the only significant predictor was the severity of injury (F = 8.48 [1, 34]; R2 = 0.30; P = 0.0063). Of the following physical and psychosocial variables--level of participation, type of sport, age, previous injury, preinjury stress, gender, mood state scales, and self-esteem--only level of participation (P < 0.0001) and type of sport (P = 0.0004) were predictors of injury. The significant preinjury and postinjury differences in mood state suggest that postinjury mood disturbances reported in previous studies are likely attributable to the occurrence of injury, are related to the severity of injury, and do not merely reflect a disturbed preinjury mood.

Affect↗

PubMed1993

Second natural history study of congenital heart defects. Materials and methods.

Results of the location and recruitment efforts and comparisons of responses from patients who cooperated at different levels in the Second Natural History Study of Congenital Heart Defects are included because they influenced the choice of analytic methods and are essential to the generalizability of the results to the entire study cohort. Included are examination and data collection protocols (e.g., protocol definitions, test procedures, and data editing), statistical methods (e.g., box plots, survival curves, multivariable models, and rate adjustment), participation results (e.g., proportional odds analysis, mortality, location, recruitment, and full participants, including comparison of questionnaire responses and comparison of questionnaire response and physician history), and a discussion.

Data Collection↗

PubMed1991

Causes of death in patients with tuberous sclerosis.

Of the 355 patients with tuberous sclerosis complex (TSC) examined at the Mayo Clinic, 49 had died (9 of causes other than TSC). We attempted to determine what pattern of organ involvement occurred most often in the 40 patients who died of TSC. One baby died of cardiac failure due to cardiac rhabdomyomas, and one child died of rupture of an aneurysm of the thoracic aorta. Eleven patients died of renal disease, which was the commonest cause of death. Ten patients died as a result of brain tumors, and four patients (who were 40 years of age or older) died of lymphangiomyomatosis of the lung. Thirteen patients with severe mental handicaps died of either status epilepticus or bronchopneumonia; in all but one of these patients, the only source of information was the death certificate. Survival curves show a decreased survival for patients with TSC in comparison with that for the general population. Patients with TSC need lifelong follow-up for early detection of potentially life-threatening complications.

Adolescent↗