Normal skin test responses in chronic marijuana users.

The cell-mediated immunity of 22 chronic marijuana smokers showed no difference from that of normal controls when evaluated by in vivo skin testing with 2,4-dinitrochlorobenzene. However, a significant difference was seen between these chronic marijuana users, all of whom could be sensitized to 2,4-dinitro-chlorobenzene, and age-matched cancer patients, who showed a decreased capacity to be sensitized.

Neuromuscular junction dysfunction in Miller Fisher syndrome.

The Miller Fisher syndrome (MFS) is a variant of Guillain-Barre syndrome with the clinical triad of areflexia, ataxia, and ophthalmoparesis. The classic pathologic mechanism of disease is considered to be peripheral nerve demyelination. We present a patient with binocular diplopia and a diagnosis of myasthenia gravis from 15 years prior. Electrophysiologic studies revealed a decremental response on repetitive nerve stimulation, suggesting recurrent myasthenia. However, pupillary light-near dissociation and areflexia were present and positive anti-GQ1b antibodies confirmed MFS. This patient highlights a developing recognition of impaired neuromuscular transmission in MFS. His presentation is discussed in the context of the animal and human literature on neuromuscular junction abnormalities in MFS.

Outcome after invasive local recurrence in patients with ductal carcinoma in situ of the breast.

PURPOSE: To detail the outcome, in terms of local recurrence, local invasive recurrence, distant recurrence, and breast cancer mortality for patients previously treated for ductal carcinoma in situ (DCIS). PATIENTS AND METHODS: Clinical, pathologic, and outcome data were collected prospectively for 707 patients with DCIS accrued from 1972 through June 1997. RESULTS: There were 74 local recurrences; 39 were noninvasive (DCIS) and 35 were invasive. Fifty-one percent of patients with invasive recurrences presented with stage 1 disease; the remainder presented with more advanced disease. Invasive local recurrence after mastectomy was a rare event that occurred in 0.8% of patients. Invasive recurrence after breast preservation was more common and occurred in 7.4% of patients. The 8-year probability of breast cancer mortality after breast preservation was 2.1%, a number that is likely to increase with longer follow-up. The 8-year breast cancer-specific mortality and distant-disease probability for the subgroup of 74 patients with locally recurrent disease was 8.8% and 20.8%, respectively. If only the 35 invasive recurrences are considered as events, the 8-year breast cancer-specific mortality and distant-disease probability was 14.4% and 27.1%, respectively. CONCLUSION: Invasive local recurrence after breast-preservation treatment for patients with DCIS is a serious event that converts patients with previous stage 0 disease to patients with disease that ranges from stage I to stage IV. These results, however, indicate that most DCIS patients with local recurrence can be salvaged.

Prospectively randomized clinical trial of three intensive chemotherapy regimens for the treatment of advanced unfavorable histology non-Hodgkin's lymphoma.

Three hundred thirty-two eligible patients with advanced (Ann Arbor stage III or IV) non-Hodgkin's lymphoma of aggressive histologic subtype (Rappaport classification diffuse histiocytic [DH], diffuse poorly differentiated lymphocytic [DPDL], diffuse mixed [DM], or diffuse undifferentiated [DU]) were randomly assigned to receive induction chemotherapy with one of three intensive regimens in a clinical trial conducted by the Eastern Cooperative Oncology Group (ECOG) between 1978 and 1983. Chemotherapy regimens consisted of cyclophosphamide, vincristine, prednisone, and doxorubicin (Adriamycin; Adria Laboratories, Columbus, OH) (COPA) administered in 3-week cycles; cyclophosphamide plus doxorubicin plus prednisone beginning day 1, with vincristine plus bleomycin day 15 of each 3-week cycle (COPA + Bleo); or cyclophosphamide plus doxorubicin plus procarbazine beginning day 1, and bleomycin plus vincristine plus prednisone beginning day 15 of each 4-week cycle (CAP-BOP). The median patient follow-up from study entry for patients still alive is 5 years. The three regimens were not significantly different with respect to complete response (CR) rates (43% to 46%), time to progression of malignant disease (median, 1.0 to 1.7 years), or survival (5-year survival, 34% to 45%), although duration of complete remission appeared to be shorter in patients receiving COPA (P = .03). COPA + Bleo and CAP-BOP were significantly more toxic than the COPA regimen. This study did not demonstrate any substantial therapeutic advantage associated with the addition of a fifth or sixth chemotherapy drug, or with treatment administered on a more frequent administration schedule, compared with the COPA regimen in this population of patients with advanced diffuse non-Hodgkin's lymphoma. The relatively small proportion of long-term disease-free survivors treated with COPA underscores the need for prospective clinical trials of new and more effective treatments for patients with these potentially curable tumors.

Schneiderian first-rank symptoms in schizophrenia.

Schneider's first-rank symptoms (FRS) are recognized by many psychiatrists worldwide as definitive criteria for establishing the diagnosis of schizophrenia. The relationships between FRS and major aspects of psychopathology were examined. Clinical course and outcome, indices of current functioning and symptom severity, premorbid adjustment, and prognostic indicators were assessed. Major comparisons were made between schizophrenics with FRS at follow-up and schizophrenics with psychotic symptoms exclusive of FRS. Positive findings in select areas of outcome functioning argue for the utility of FRS. However, several findings indicated that FRS were not more effective than non-Schneiderian psychotic symptoms in delineating central characteristics of the schizophrenic syndrome; they may identify a subgroup of schizophrenics with a more chronic course, but they do not appear to have the unique importance or diagnostic specificity that has been accorded them.

Disordered thinking.

To evaluate formulations that thought disorder at the posthospital phase identifies a subgroup of nuclear schizophrenics with poor outcomes, 77 patients from a longitudinal project were followed up on major dimensions of psychopathology linked to nuclear schizophrenia. The data indicate that (1) schizophrenics were more thought disordered than were nonschizophrenics at the posthospital phase; (2) thought-disordered schizophrenics had only slightly poorer scores on classic prognostic indicators associated with poor outcomes; (3) a subgroup of early chronic schizophrenics were not severely thought disordered; (4) almost all severely thought-disordered schizophrenics demonstrated clear evidence of delusional activity at follow-up; and (5) thought-disordered schizophrenics had poorer outcomes. The overall results fit in with formulations that a severe thought disorder is one of several major features of schizophrenia. The data suggest that posthospital thought disorder identifies a subgroup of poor-outcome schizophrenics, although some non-thought-disordered schizophrenics also show poor outcomes.

Thought pathology in manic and schizophrenic patients. Its occurrence at hospital admission and seven weeks later.

To evaluate the extent and persistence of thought pathology in manic patients, 113 manic, schizophrenic, and nonpsychotic patients were assessed at the acute phase, and a subsample was reevaluated seven weeks later. Another subsample of 55 patients was assessed medication free at the acute phase. Three major indices of thought disorder were used. The data indicate that (1) most hospitalized manics are severely thought disordered; (2) hospitalized manics are as thought disordered as schizophrenics; (3) unmedicated manics are as severely thought disordered as unmedicated schizophrenics; (4) both manics' and schizophrenics' thought disorders improve after the acute phase; (5) even after the acute phase, some manics show severe thought pathology. The results support formulations that thought disorder is not unique to schizophrenia. Some factors involved in manic and schizophrenic thought pathology are similar. There may be a general psychosis factor that cuts across psychotic diagnoses.

A longitudinal study of thought disorder in manic patients.

To study the persistence of thought disorder in manic patients, 34 manic patients were compared with 30 schizophrenic and 30 nonpsychotic patients on four indexes of thought pathology at two phases of disorder: during the acute inpatient phase and one year after hospitalization. Patients were also compared with a control sample of 34 normal subjects. The data indicated that during the acute in hospital phase, both manic and schizophrenic patients were severely thought disordered; at follow-up, a subsample of manic patients showed severe thought disorder; despite the severe thought disorder found at follow-up in some manic and schizophrenic patients, both groups showed a significant reduction of thought pathology at follow-up; and there was a trend for a larger reduction of thought disorder in manic than in schizophrenic patients. The difference, however, was not significant when initial levels of severity were controlled.

Effect of splenectomy on teardrop-shaped erythrocytes in agnogenic myeloid metaplasia.

Teardrop-shaped erythrocytes (TD) are frequently observed in the peripheral blood of patients with agnogenic myeloid metaplasia (AMM). These deformed cells may result from the myelofibrosis or the extramedullary hematopoiesis in the spleen. To determine the influence of the spleen on TD formation, we reviewed the presplenectomy (pre-S) and postsplenectomy (post-S) peripheral blood smears from 13 patients with AMM. The splenectomy was performed for a variety of reasons, including symptomatic hypersplenism or splenomegaly. The average number of TDs per 1,000 RBCs in the pre-S smears was 42 (range, 15 to 112 TDs), compared with 11 TDs in the post-S smears (range, 6 to 20 TDs)(P = less than .001). Only one of the 13 patients failed to exhibit this decrease in TDs post-S. There was no definite correlation between the number of TDs and the weight of the spleen removed at surgery, the interval since surgery, or age and sex of the patient. Based on this fourfold decrease in the number of TDs post-S, we conclude that the spleen in AMM play an important role in TD formation.

Risk factors for 30-day mortality in elderly patients with lower respiratory tract infection. Community-based study.

BACKGROUND: Pneumonia is a major cause of death in the elderly, but there are few studies of risk factors for death that include both ambulatory and nursing home patients. OBJECTIVE: To assess factors associated with 30-day mortality in a population-based study of older adults with lower respiratory tract infection. METHODS: Identification of (1) a previously identified retrospective cohort of all residents of Rochester, Minn, aged 65 years or older who experienced a first episode of pneumonia or bronchitis during a calendar year and (2) the risk factors associated with 30-day mortality through review of complete inpatient and ambulatory medical records. Logistic regression was used to identify significant independent risk factors for 30-day mortality. RESULTS: A total of 413 adults aged 65 years or older were identified. The independent factors for 30-day mortality were atypical symptoms (odds ratio [OR], 4.98; 95% confidence interval [CI], 2.14-11.60), neurologic illness (OR, 3.92; 95% CI, 1.47-6.59), current diagnosis of cancer (OR, 6.2; 95% CI, 2.40-15.99), and recent or current use of antibiotics (OR, 3.13; 95% CI, 1.45-6.77). CONCLUSIONS: Malignancy and neurologic disease are well-recognized conditions that identify patients with lower respiratory tract infections who have a high risk of death within 30 days. An atypical presentation with confusion, lethargy, poor eating, or recent or current antibiotic use also identifies patients, with a high risk of 30-day mortality.

Life-sustaining treatment. A prospective study of patients with DNR orders in a teaching hospital.

We conducted a prospective survey of attending, resident, and intern physicians who had written a "do not resuscitate" (DNR) order for 93 patients in their care. After writing a DNR order, 11% of respondents would still use chest compression if their patient experienced a cardiopulmonary arrest. Many physicians did not plan to withdraw therapy except intensive care, but most physicians planned to withhold a spectrum of life-sustaining therapies, from hemodialysis (86%) to intravenous fluids (21%). Attending and house-staff physicians generally agreed on whether to withdraw a given therapy or not but frequently disagreed on whether to withhold a therapy or not. After patient discharge or death, 88 charts were reviewed. None of the 88 patients was coded. Physicians initiated 68 life sustaining therapies in 43 patients and discontinued 64 therapies in 34 patients; there was no change in management in 31 patients. We conclude that individual physicians interpret the DNR order differently. These orders often are associated with the discontinuation or noninitiation of life-sustaining therapies other than emergency CPR.

The clinical utility of the Ca19-9 radioimmunoassay for the diagnosis of pancreatic cancer presenting as pain or weight loss. A cost-effectiveness analysis.

CA 19-9 is a promising radioimmunoassay for the detection of pancreatic cancer, but its clinical role and cost-effectiveness are not yet known. To investigate these factors, we used clinical decision analysis to study diagnostic strategies for patients with suspected pancreatic cancer presenting as pain or weight loss. Comprehensive diagnostic strategies were developed to reflect current and future patterns of practice utilizing CA19-9 radioimmunoassay (RIA) to yield biopsy-proved cancer or confidently exclude its presence. The performance of the strategies beginning with CA19-9 RIA and ultrasonography were equivalent in positive and negative predictive values over a range of prevalence of pancreatic cancer from 0.02 to 0.15. At higher prevalence, the negative predictive value of the ultrasonography strategy became significantly better. The CA19-9 RIA strategy used fewer noninvasive tests, endoscopic retrograde cholangiopancreatographic procedures, and invasive radiologic studies than did the ultrasonography strategy at each prevalence. The health care costs ranged between $848 and $1413 per patient for the CA19-9 RIA strategy and $1186 and $1848 per patient for the ultrasonography strategy. We conclude that the CA19-9 RIA is a useful, cost-effective initial test for the examination of patients with suspected pancreatic cancer.

The probability of malignancy in solitary pulmonary nodules. Application to small radiologically indeterminate nodules.

BACKGROUND: A clinical prediction model to identify malignant nodules based on clinical data and radiological characteristics of lung nodules was derived using logistic regression from a random sample of patients (n = 419) and tested on data from a separate group of patients (n = 210). OBJECTIVE: To use multivariate logistic regression to estimate the probability of malignancy in radiologically indeterminate solitary pulmonary nodules (SPNs) in a clinically relevant subset of patients with SPNs that measured between 4 and 30 mm in diameter. PATIENTS AND METHODS: A retrospective cohort study at a multispecialty group practice included 629 patients (320 men, 309 women) with newly discovered (between January 1, 1984, and May 1, 1986) 4- to 30-mm radiologically indeterminate SPNs on chest radiography. Patients with a diagnosis of cancer within 5 years prior to the discovery of the nodule were excluded. Clinical data included age, sex, cigarette-smoking status, and history of extrathoracic malignant neoplasm, asbestos exposure, and chronic interstitial or obstructive lung disease; chest radiological data included the diameter, location, edge characteristics (eg, lobulation, spiculation, and shagginess), and other characteristics (eg, cavitation) of the SPNs. Predictors were identified in a random sample of two thirds of the patients and tested in the remaining one third. RESULTS: Sixty-five percent of the nodules were benign, 23% were malignant, and 12% were indeterminate. Three clinical characteristics (age, cigarette-smoking status, and history of cancer [diagnosis, > or = 5 years ago]) and 3 radiological characteristics (diameter, spiculation, and upper lobe location of the SPNs) were independent predictors of malignancy. The area (+/-SE) under the evaluated receiver operating characteristic curve was 0.8328 +/- 0.0226. CONCLUSION: Three clinical and 3 radiographic characteristics predicted the malignancy in radiologically indeterminate SPNs.

Prophylactic agents for venous thrombosis in elective hip surgery. Meta-analysis of studies using venographic assessment.

BACKGROUND: We determined the relative efficacy of various agents or combinations of agents in the prophylaxis of deep venous thrombosis after elective hip arthroplasty. METHODS: Peer-reviewed, English-language, human studies articles from 1975 through 1991 were obtained through a MEDLINE database search. Additional references were obtained from bibliographies. Articles that compared the effect of two or more prophylactic agents or placebo in preventing deep venous thrombosis as assessed by venography were selected for further review. Only studies of elective hip surgery in which all patients had venographic screening for thrombosis were included. Twenty-three of 101 studies met these criteria. Data were abstracted by one of us. Methodologic criteria and outcome data from each study were recorded and analyzed. RESULTS: There was significant heterogeneity in the deep venous thrombosis rate among studies. Although the rates were lowest for low-molecular-weight heparin with or without the use of stockings, adjusted-dose heparin, and warfarin, many agents had similar low rates. There was less heterogeneity when the relative risk was used as a summary statistic for studies in which two agents were compared. With pairwise comparisons, low-molecular-weight heparin performed better than every agent with which it was compared. Other agents performed well but were not consistently better. CONCLUSIONS: Multiple agents or combinations are effective prophylaxis for deep venous thrombosis, but none decreases the rate to zero. There was overlap in the 95% confidence intervals for the probability of deep venous thrombosis for various agents and especially for the probabilities for proximal thrombi. Many agents have not been compared directly with each other, but low-molecular-weight heparin consistently performed well.

Outcome analysis of 34 pregnancies in women with essential thrombocythemia.

OBJECTIVE: To evaluate the clinical impact of essential thrombocythemia on the outcome of pregnancy or vice versa. DESIGN: A retrospective study. SETTING: All patients were seen at our tertiary referral center, and most were followed up by their local physicians. PATIENTS: From 1975 through 1991, 73 women younger than 50 years with essential thrombocythemia were seen at our institution. All patients were followed up through patient or physician contact. A detailed obstetric history, including peripartum complications and management, was obtained. RESULTS: Among the 73 women, 34 pregnancies occurred in 18 patients. There were two uncomplicated elective abortions and one ectopic pregnancy. Of the 31 other pregnancies, 17 (55%) resulted in live birth and 14 (45%) ended in spontaneous abortion (all but two in the first trimester). Abortion could not be predicted from history of disease complications before or during pregnancy or by the presence or absence of specific therapy during pregnancy. Preconception platelet counts in women whose pregnancies resulted in live birth were similar to those of women whose pregnancies ended in abortion. Other complications during pregnancy were rare. CONCLUSIONS: Patients with essential thrombocythemia have an increased risk of first-trimester abortion, which does not appear to be predictable or influenced by therapy. However, most patients are able to carry pregnancies to term with little or no risk of obstetric or thrombohemorrhagic complications during or after delivery. Overall, specific therapy during pregnancy did not appear to modify the clinical outcome, and the benefit of platelet apheresis during delivery could not be substantiated.

Organizing pneumonia. Features and prognosis of cryptogenic, secondary, and focal variants.

BACKGROUND: Organizing pneumonia (OP) is a non-specific response to many types of lung injury. Clinicians frequently encounter pathology reports of OP in patients with no underlying condition (cryptogenic OP, also known as BOOP or bronchiolitis obliterans OP) or in association with drugs or nonpulmonary disease. The goals of this study are to describe the clinical course and outcomes in patients with 3 clinical variants of OP. METHODS: A retrospective study of patients with OP seen at the Mayo Clinic, Rochester, Minn, from January 1, 1984, through June 30, 1994, was conducted. Initial features were obtained from medical records. Chest radiographs and pathology specimens were reviewed for this study. Resolution, relapse, and survival were obtained from medical records and a follow-up patient questionnaire. RESULTS: Seventy-four patients had pathologically confirmed OP. Organizing pneumonia was classified into 3 clinical groups: symptomatic cryptogenic OP; symptomatic OP related to underlying hematologic malignant neoplasm, collagen vascular disease, or drugs (secondary OP); and asymptomatic OP presenting as a focal nodule (focal OP). Thirty-seven patients (50%) had cryptogenic OP and 27 patients (36%) had secondary OP. No difference was found between cryptogenic and secondary OP in type or severity of symptoms, signs, laboratory and pulmonary function tests, or radiologic or pathologic findings. Corticosteroids were given at a similar initial dose (prednisone, about 50 mg/d). Resolution of symptoms was more frequent in patients with cryptogenic OP than those with secondary OP. Relapse was infrequent in both of these groups. Five-year survival was higher in patients with cryptogenic OP (73%) than in secondary OP (44%), and respiratory-related deaths were more frequent in patients with secondary OP. Organizing pneumonia was an asymptomatic focal rounded opacity in 10 patients (14%), most often detected on chest radiograph and diagnosed on lung biopsy done for suspicion of lung cancer. Patients with focal OP required no treatment and had no relapse or respiratory-related deaths. CONCLUSIONS: Clinical classification of OP is useful to predict clinical course and outcome. Cryptogenic OP most often was a symptomatic bilateral lung process that had an overall favorable prognosis with prolonged corticosteroid therapy. Patients with secondary OP had a high mortality rate when the disease was associated with predisposing conditions or drugs. Patients with asymptomatic focal OP had an excellent prognosis.

Trends in the incidence of deep vein thrombosis and pulmonary embolism: a 25-year population-based study.

BACKGROUND: The incidence of venous thromboembolism has not been well described, and there are no studies of long-term trends in the incidence of venous thromboembolism. OBJECTIVES: To estimate the incidence of deep vein thrombosis and pulmonary embolism and to describe trends in incidence. METHODS: We performed a retrospective review of the complete medical records from a population-based inception cohort of 2218 patients who resided within Olmsted County, Minnesota, and had an incident deep vein thrombosis or pulmonary embolism during the 25-year period from 1966 through 1990. RESULTS: The overall average age- and sex-adjusted annual incidence of venous thromboembolism was 117 per 100000 (deep vein thrombosis, 48 per 100000; pulmonary embolism, 69 per 100000), with higher age-adjusted rates among males than females (130 vs 110 per 100000, respectively). The incidence of venous thromboembolism rose markedly with increasing age for both sexes, with pulmonary embolism accounting for most of the increase. The incidence of pulmonary embolism was approximately 45% lower during the last 15 years of the study for both sexes and all age strata, while the incidence of deep vein thrombosis remained constant for males across all age strata, decreased for females younger than 55 years, and increased for women older than 60 years. CONCLUSIONS: Venous thromboembolism is a major national health problem, especially among the elderly. While the incidence of pulmonary embolism has decreased over time, the incidence of deep vein thrombosis remains unchanged for men and is increasing for older women. These findings emphasize the need for more accurate identification of patients at risk for venous thromboembolism, as well as a safe and effective prophylaxis.

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.

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.