A schematic analysis of the Unified Medical Language System

The UMLS is a complex collection of medical terms and relationships derived from standard classifications. Appreciating the scope and layout of these relations from text descriptions of relational schema is difficult. The graphical technique of Logical Data Structure (LDS) representation was employed to illustrate the UMLS schema as a data abstraction, affording additional insights that might otherwise escape notice. An LDS representation of the Metathesaurus offers the following advantages: 1) the separation of a viewpoint from physical data structures enables a global outline of the contents; 2) the graphical map makes the interrelation of data visible; and 3) the logical entities explicitly reflect the decision-making which was implicit or ambiguous in the relational scheme.

Latent Semantic Indexing of medical diagnoses using UMLS semantic structures

The relational files within the UMLS Metathesaurus contain rich semantic associations to main concepts. We invoked the technique of Latent Semantic Indexing to generate information matrices based on these relationships and created "semantic vectors" using singular value decomposition. Evaluations were made on the complete set and subsets of Metathesaurus main concepts with the semantic type "Disease or Syndrome." Real number matrices were created with main concepts, lexical variants, synonyms, and associated expressions. Ancestors, children, siblings, and related terms were added to alternative matrices, preserving the hierarchical direction of the relation as the imaginary component of a complex number. Preliminary evaluation suggests that this technique is robust. A major advantage is the exploitation of semantic features which derive from a statistical decomposition of UMLS structures, possibly reducing dependence on the tedious construction of semantic frames by humans.

Validity of self-reported waist and hip circumferences in men and women

Recent epidemiologic evidence indicates an association between fat distribution and many diseases. To assess the validity of circumference measurements obtained by self-report, the authors analyzed data from 123 men aged 40-75 years and 140 women aged 41-65 years, drawn from two large ongoing prospective studies. On mailed questionnaires, subjects were asked to measure and record their weight and waist and hip circumferences. These data were compared with standardized measurements taken approximately six months apart by technicians who visited participants at their homes. Crude Pearson correlations between self-reported waist circumferences and the average of two technician-measured waist circumferences were 0.95 for men and 0.89 for women. Similar correlations for hip measurements were 0.88 for men and 0.84 for women, and for waist-to-hip ratios, 0.69 for men and 0.70 for women. After adjusting for age and body mass index (kg/m2), correlations for waist-to-hip ratios were 0.55 for men and 0.58 for women. Correlations became stronger after correcting for random within-person variability from daily or seasonal fluctuations. Self-reported and measured weights were highly correlated: 0.97 for men and 0.97 for women. Self-reported waist, hip, and weight measurements appear reasonably valid. The moderate degree of measurement error for the ratio of self-reported waist and hip circumferences, however, implies that previously reported associations based on self-report of these measures may have been appreciably underestimated.

Predictors of selenium concentration in human toenails

To assess the validity of the selenium concentration in human toenails as a measure of selenium intake and to determine other correlates of toenail selenium level, the authors examined the predictors of toenail selenium within two subgroups of a large cohort study of US women. Mean toenail selenium was higher among 38 consumers of selenium supplements (0.904 micrograms/g, standard deviation (SD) 0.217) than among 96 nonusers (0.748 micrograms/g, SD 0.149; p less than 0.001), and a dose-response relation was observed among supplement users (Spearman's r = 0.32; p = 0.05). In a second subgroup of 677 women, selenium supplement use was also associated with higher mean toenail selenium (0.906 micrograms/g, SD 0.214, among 18 users and 0.801 micrograms/g, SD 0.148, among 659 nonusers; p = 0.02), and the dose-response relation was also significant (Spearman's r = 0.50; p = 0.03). The geographic variation in toenail selenium levels was consistent with the geographic distribution of selenium in forage crops. Toenail selenium declined with age and was significantly reduced among cigarette smokers (mean = 0.746, SD 0.124, among 146 current smokers and mean = 0.817, SD 0.159, among 311 never smokers; p less than 0.001) but was not materially affected by alcohol consumption. A dietary selenium score calculated from a food frequency questionnaire failed to predict toenail selenium level, demonstrating the suspected inability of diet questionnaires to measure individual selenium intake because of the highly variable selenium composition of different samples of the same food.(ABSTRACT TRUNCATED AT 250 WORDS)

Basal cell carcinoma. A population-based incidence study in Rochester, Minnesota

Population-based annual incidence rates for histologically proved basal cell carcinoma were derived from the records linkage system of the Rochester Epidemiology Program Project. Residents of Rochester, Minnesota, during the years 1976 to 1984, formed the observational cohort. A total of 657 first episodes of basal cell carcinoma were observed. Annual incidence rates per 100,000 persons in the Rochester population, standardized to the 1980 U.S. white population, were 175 for men, 124 for women, and 146 combined. Recurrent or subsequent basal cell carcinoma was observed among 30% of patients during an average of 4.5 years of follow-up; no metastatic lesions occurred. The rates of recurrence were similar after complete excision or treatment with curettage and cauterization in these observational data.

Squamous cell carcinoma. A population-based incidence study in Rochester, Minn

The records linkage resources of the Rochester Epidemiology Program Project were used to identify 169 incident cases of invasive squamous cell carcinoma of the skin in the population of Rochester, Minn, between 1976 and 1984. The overall age-standardized incidence was 38.8/100,000 persons (63.1 in men; 22.5 in women). Metastasis occurred in 3.6%, and during an average of 3.8 years of follow-up, recurrence was seen in 3.6% while subsequent new lesions occurred in 12%. The demographics and course of patients with squamous cell carcinoma were different from either those of Bowen's disease or basal cell carcinoma in these population-based data.

Effect of transport conditions on the stability of biochemical markers in blood

We examined the stability of lipids, carotenoids, alpha-tocopherol, and endogenous hormones in plasma prepared from whole blood that had been mailed to a central location for processing. Initially, to simulate transport conditions, whole-blood samples were stored in the laboratory, either at room temperature or cooled, for up to 72 h before processing. In the latter samples, lipid concentrations changed up to 1.4% per day, carotenoids up to -5.5%, and hormones up to 9.5%. In a second study, analyte concentrations in plasma from cooled whole blood mailed via overnight courier were compared with those from plasma that had been immediately separated, frozen, and mailed via overnight courier. Concentrations of cholesterol, high-density lipoprotein subfraction 3, apolipoprotein B, and retinol were stable. Overall, for each marker except estradiol, the between-person variation was at least twice the within-person variation. In a third study, at least 340 micrograms of DNA was recovered from 30 mL of cool-shipped whole blood. Our results indicate that shipping whole-blood samples by overnight courier is feasible for assay of several biochemical markers of interest in epidemiological research.

Effect of transport conditions on the stability of biochemical markers in blood

We examined the stability of lipids, carotenoids, alpha-tocopherol, and endogenous hormones in plasma prepared from whole blood that had been mailed to a central location for processing. Initially, to simulate transport conditions, whole-blood samples were stored in the laboratory, either at room temperature or cooled, for up to 72 h before processing. In the latter samples, lipid concentrations changed up to 1.4% per day, carotenoids up to -5.5%, and hormones up to 9.5%. In a second study, analyte concentrations in plasma from cooled whole blood mailed via overnight courier were compared with those from plasma that had been immediately separated, frozen, and mailed via overnight courier. Concentrations of cholesterol, high-density lipoprotein subfraction 3, apolipoprotein B, and retinol were stable. Overall, for each marker except estradiol, the between-person variation was at least twice the within-person variation. In a third study, at least 340 micrograms of DNA was recovered from 30 mL of cool-shipped whole blood. Our results indicate that shipping whole-blood samples by overnight courier is feasible for assay of several biochemical markers of interest in epidemiological research.

Risk for colorectal adenocarcinoma in pernicious anemia. A population-based cohort study

STUDY OBJECTIVE

To determine the long-term risk for colorectal cancer among patients with pernicious anemia.

DESIGN

Historical cohort study.

SETTING

Population-based inception cohort of Rochester, Minnesota, residents.

PATIENTS AND METHODS

We identified 150 Rochester residents who had the onset of pernicious anemia during the 30-year period from 1950 through 1979, and we followed this cohort for 1664 person-years of observation. The observed risk for subsequent colorectal cancer in the cohort was compared with that expected based on incidence rates of colon and rectal cancer for the local population.

MEASUREMENTS AND MAIN RESULTS

There were 14 cases of colorectal cancer among the 150 patients with pernicious anemia (where 10.5 cases were expected), and 9 of these cases were found after the diagnosis of pernicious anemia was established (where 5.1 cases were expected). The relative risk for colon cancer at any time after the diagnosis of pernicious anemia was 1.8 (CI, 0.8 to 3.3). The relative risk was greatest (4.1; CI, 1.7 to 8.7) in the 5-year period immediately after the diagnosis of pernicious anemia; during this period, 7 cases of colon cancers were observed but only 1.7 were expected (P less than 0.0001).

CONCLUSION

Although the overall risk does not achieve statistical significance, patients with pernicious anemia may have an increased risk for colorectal adenocarcinoma in the 5 years after diagnosis.

Sex hormones and lipoproteins in men

PURPOSE

To clarify the conflicting evidence of an association between endogenous sex hormones and lipoprotein metabolism in men, we examined the relationship between sex hormone levels, total cholesterol, and high-density lipoprotein cholesterol (HDL-C), taking into account the coronary artery disease (CAD) status of the subjects.

PATIENTS AND METHODS

Sex hormone levels, total cholesterol, and HDL-C were measured in 67 men with CAD from among 191 consecutive male patients between the ages of 25 and 75 undergoing coronary angiography, in 26 men without angiographic evidence of CAD, and in 55 men who were clinically free of CAD.

RESULTS

There was a consistently positive correlation between total estradiol or calculated free estradiol and both total cholesterol and HDL-C, which persisted after adjustment for potential confounders. Total cholesterol was associated with total testosterone after controlling for age, adiposity, and the presence or absence of CAD, but not with calculated free testosterone. No association was noted between total testosterone or calculated free testosterone and HDL-C. A significant interaction was observed between estradiol and testosterone with respect to total cholesterol.

CONCLUSION

This study demonstrates an association between sex hormone levels and lipoprotein metabolism, specifically between estradiol levels and both total cholesterol and HDL-C. Unlike most previous investigators, we were able both to control for the CAD status of our subjects and to consider unbound, biologically active hormone levels. In addition, we documented a complex interaction between endogenous testosterone and estradiol in relation to lipoprotein levels; this association should be considered in future studies.

Social and economic factors in the choice of lung cancer treatment. A population-based study in two rural states

We reviewed 1808 hospital charts representing virtually all patients given a diagnosis of non-small-cell lung cancer in New Hampshire and Vermont between 1973 and 1976 and found that the treatment of patients varied according to their marital status, medical insurance coverage, and proximity to a cancer-treatment center. Patients were more likely to be treated with surgery if they were married (odds ratio, 1.67; 95 percent confidence interval, 1.08 to 2.57) or had private medical insurance (1.52; 1.03 to 2.26). Among patients who did not have surgery, those with private insurance were more likely to receive another form of anticancer therapy--either radiation or chemotherapy (1.57; 1.18 to 2.09). Residing farther from a cancer-treatment center was associated with a greater chance of having surgery. Patients 75 years of age and older were less likely to have surgery (0.16; 0.08 to 0.35) or any other tumor-directed therapy (0.32; 0.19 to 0.54). The relation between the type of treatment and a patient's characteristics was not based on apparent differences in tumor stage or functional status, although both these factors were also strongly predictive of the type of treatment. Despite the fact that privately insured and married patients were more aggressively treated, they did not survive longer after diagnosis. We conclude that for non-small-cell lung cancer, socio-economic as well as medical factors determine treatment.

Penicillin and the marked decrease in morbidity and mortality from rheumatic fever in the United States

There has been a marked decline in mortality due to rheumatic fever in the United States. We present evidence for the important role of penicillin in changing the severity of rheumatic carditis, beginning about 1946. Since that year, mortality due to rheumatic carditis has rapidly decreased to zero at the hospital we studied (House of the Good Samaritan, Boston), the rate of loss of all murmurs in patients at the study hospital accelerated simultaneously and exceeded 40 percent by 1970, and the rates of decline in national mortality due to rheumatic carditis accelerated fourfold with the advent of antibiotics. These data, together with reports of recent outbreaks of rheumatic fever, emphasize the importance of continued efforts to diagnose and treat Group A streptococcal pharyngitis.

Sex hormones and coronary artery disease

Previous investigators have found an increased risk of coronary heart disease in men with high levels of circulating estrogens. To elucidate further this relationship, a case-control study of atherosclerotic coronary artery disease (ASCAD) and sex hormones was undertaken in male patients. Hormone levels in men with severe ASCAD documented at angiography were compared with those in men found to be virtually free from disease and with those in a group of control subjects without signs or symptoms of ASCAD. Significantly lower total testosterone levels were observed among men with severe ASCAD compared with either control group; the free testosterone level was significantly lower than in angiographically disease-free control subjects. The same pattern of hormone levels persisted after control of covariates. Epidemiologic analysis demonstrated a fivefold decrease in risk for severe ASCAD between the lowest and the highest quartile of total testosterone. No overall pattern of association was seen between ASCAD and free or total estrogens.

Risk factors for endemic giardiasis

In a mail survey, 171 Hitchcock Clinic patients with giardiasis were compared with an age- and sex-matched control group of 684 clinic patients with respect to potential risk factors. Households with shallow well or surface water sources had an odds ratio (OR) for giardiasis of 2.1 (95% confidence interval (95%CI) 1.3-3.2) compared with households with drilled well or municipal water supply. Other observed risks include family member in day care program (OR 2.2 95%CI 1.3-3.7) and family member with diagnosed giardiasis (OR 17, 95%CI 7.4-37). Previously reported risks such as travel out of country (OR 3.2, 95%CI 1.5-7.2) and camping (OR 1.7, 95%CI 0.9-3.2) were also observed. Virtually no giardiasis risk was observed associated with report of dog or barnyard animal proximity. Control for confounding and adjustment for recall and non-response bias does not materially alter the risk estimates. We suggest that shallow well or surface household water source is an important and previously unrecognized giardiasis risk factor.

Presenting conditions of 1539 population-based lung cancer patients by cell type and stage in New Hampshire and Vermont

The authors identified all newly diagnosed lung cancer cases in New Hampshire and Vermont for the period 1973 through 1976 and abstracted clinical data on presenting symptoms and findings from their hospital records. Microscopy slides were also reviewed, when possible, to confirm cell type. The most frequent presenting symptoms were weight loss (46%) and cough (45%). Other common symptoms were dyspnea (37%), weakness (34%), chest pain (27%), and hemoptysis (27%). The presence of symptoms and findings was in general related to disease stage but bore little relationship to cell type. These results differ from those of previously reported case series that were based on surgical, radiation therapy, or Veterans Hospital groups, but the current data agree closely with those from another population-based series in Finland.