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Biomedical subjects

R Detels

Publications and source records attributed to R Detels.

At least 181 records · Page 10Linked to original sources
PubMed1983

Underlying cause of death as recorded for multiple sclerosis patients: associated factors.

The coding of multiple sclerosis (MS) as underlying cause of death (UCD) on the death certificate provides an important epidemiologic resource for both descriptive and analytic studies. However, not all deaths among MS patients will be so coded. We investigated the effect on estimated occurrence of MS and on characteristics of MS patients when only UCD codes are used to identify cases. Of 2329 MS patients living in Los Angeles County (California) or King/Pierce Counties (Washington) in 1970, 438 had died by 1980. Only 53% of the deaths were coded to MS; 47% were attributed to other causes. Based on our comparisons, the use of only MS-coded deaths to describe decedents would: underestimate the age at MS onset; overestimate the female:male ratio; underestimate age at death; and underestimate duration of MS. Also, the percentage of MS-coded deaths decreased with lengthening duration of follow-up of these prevalent cases. The effect of using only UCD codes to report characteristics of decedents with other chronic diseases may well be similar.

Adult↗
PubMed1983

Emergency room admissions, meteorologic variables, and air pollutants: a path analysis.

Daily hospital emergency room admissions at hospitals located within 8 km of Los Angeles Basin monitoring stations at Long Beach, Lennox, Azusa, and Riverside, California, were examined for correlations with pollutant and meteorologic variables for 1974-1975. By conventional correlation and regression with lagged and temporospatial analysis, the authors could not distinguish effects of pollution by particulate sulfate from those due to meteorologic variables and oxidant. The authors use a variety of structural models and path analysis to estimate "direct" effects on emergency room admissions of maximum temperature, humidity, wind velocity, barometric pressure, carbon monoxide, sulfur dioxide, nitric oxide, high-volume suspended particulates, coefficient of haze, nitrogen dioxide, oxidant, and sulfate. Criteria for choice of models included plausibility of pairwise dependence relationships, magnitude of the correlations with emergency room admissions, and examination of the partial correlation matrix. Their results show that a variety of models gave similarly large path coefficients for a given location for the following variables: maximum temperature at each site; sulfate at Long Beach and Lennox but not at Riverside which nevertheless had the highest sulfate means; oxidant at Azusa which had the highest oxidant levels. At other locations, despite substantial and significantly elevated correlation coefficients, oxidant had a small or negative path coefficient. After considering other possible factors, the authors conclude that sulfate pollution at Lennox and Long Beach had an important and possibly causal association with demand for emergency room admissions. This demonstrates the usefulness of using a variety of structural models in the analysis of ecologic data.

Air Pollution↗
PubMed1983

Comparison of lung function in young nonsmokers and smokers before and after initiation of the smoking habit. A prospective study.

It has been suggested that young persons who smoke have better lung function initially than those who remain nonsmokers. To examine this possibility prospectively, we analyzed respiratory questionnaire responses and lung function results in residents of Burbank and Lancaster, California, who had completed field screening studies of respiratory status at 2 times 5 yr apart. At Time 1 and Time 2, we calculated the age- and height-adjusted values for forced vital capacity (FVC) and forced expiratory volume in one second (FEV) of all white residents who at Time 1 were 13 to 23 yr of age and did not smoke tobacco. Dividing these into 2 groups, "starters" and "nonsmokers," we used analysis of covariance for males and females with height and age as covariates and compared lung function values at Times 1 and 2 and changes in lung function between these times. Among males at Time 1, FVC, FEV, peak expiratory flow, and maximal flow after exhalation of 25% of FVC were significantly larger for starters than for nonsmokers. At Time 2, values for these same indexes (except for FVC) were no longer significantly different between starters and nonsmokers. Our findings suggest that (1) relatively poor lung function may discourage young males (but not young females) from becoming regular tobacco smokers; (2) prediction equations based on so-called normal populations of nonsmokers might underestimate normal lung function, and (3) the adverse effect of smoking on lung function may be even greater than that estimated from cross-sectional studies.

Adolescent↗
PubMed1983

The acquired immunodeficiency syndrome.

Recently, a new epidemic illness, the acquired immunodeficiency syndrome, has dramatically emerged in the United States, Europe, and Haiti. The syndrome represents an unprecedented epidemic form of immunodeficiency involving prominent defects of the T-lymphocyte arm of the immune system. Pneumocystis carinii pneumonia, other opportunistic infections, and the previously rare cancer, Kaposi's sarcoma, are the most conspicuous illnesses that have this profound state of immune compromise as their underlying basis. Two years after the onset of clinical illness the case-fatality rate may exceed 90%. A steadily growing body of epidemiologic evidence indicates an infectious (probably viral) cause of the immunodeficiency although the responsible agent(s) remains obscure. Critical issues surrounding the diagnosis, screening of blood products, treatment of complicating infections and cancers, and prognosis for immunologic recovery in affected persons are unresolved. The identification of the cause of acquired immunodeficiency syndrome and the institution of effective preventive measures require the urgent attention of the medical and scientific community worldwide.

Acquired Immunodeficiency Syndrome↗
PubMed1982

Factors associated with a malignant or benign course of multiple sclerosis.

Eight hundred thirty-four patients with multiple sclerosis (MS) in King and Pierce Counties, Washington, and in Los Angeles County, California, with symptomatic onset between 1960 and 1969 were followed up for disability status in 1980. A higher proportion of the 375 patients who were not walking or deceased in 1980 had a late age of onset, resided in Los Angeles County, had motor or coordination symptoms at onset, and reported adverse responses to heat exposure and favorable responses to cold exposure, whereas a higher proportion of the 299 patients still walking without aids had early onset age and vision, speech, or sensory symptoms, or all three, at onset. The results suggest (1) that both host factors (age at first manifestation of symptoms and types of symptoms at onset) and environmental factors (place of residence and exposure to heat and cold) are determinants of disease course and (2) that most patients with MS should avoid exposure to heat.

Adult↗
PubMed1982

Factors associated with a rapid course of multiple sclerosis.

A cohort of 886 cases of multiple sclerosis (MS) who had onset between Jan 1, 1960, and Dec 31, 1969, and who were resident in 1970 in either a low-prevalence area (Los Angeles County, California, 560 cases) or in a high-prevalence area (King and Pierce Counties, Washington, 326 cases) were followed up for changes in disability status through Dec 31, 1979. Cases had to meet the modified Schumacher criteria for definite/probable MS and to have had a diagnosis of MS or equivalent by a physician. Onset year of disease was determined by onset of the earliest reported symptom. Disability status was determined at intake by an interviewer-administered questionnaire and in subsequent years by an annual mailed questionnaire (self-reported disability status). Progression to a nonambulatory status or death was significantly greater among (1) patients with an older age at onset, (2) patients with a rapid early course, (3) males, and (4) residents of Los Angeles County.

Adult↗
PubMed1982

The UCLA population studies of chronic obstructive respiratory disease. 5. Agreement and disagreement of tests in identifying abnormal lung function.

The relative sensitivity and specificity of symptoms, spirometry, the flow-volume (FV) curve, the single-breath nitrogen test (SBNT), and specific airway conductance (SGaw) were estimated by cross comparison of these tests with the FEV1/FVC ratio and other tests in 1,201 residents of Los Angeles. Spirometry and the flow-volume curve were estimated to be the most sensitive, yet reasonably specific composite measures, and FEV1/FVC and V75 to be the most sensitive individual indices. Among current smokers, FEV1/FVC was more frequently abnormal (23 percent) than FEF25-75% (16 percent), showed higher concordance with an abnormal FEF25-75% (88 percent), and identified a greater percentage of individuals as abnormal when the FEF25-75% was normal (9 percent) than vice versa. SGaw and SBNT showed a poor concordance with FEV1/FVC and identified more individuals as abnormal who had a normal FEV1/FVC. Although the proportion of current smokers with productive cough was relatively high (26 percent), none of the function tests showed a reasonable concordance with this symptom. These findings suggest that: 1) spirometry, the flow-volume curve, V75 and FEV1/FVC are relatively sensitive and specific indicators of respiratory impairment; 2) spirometry and the FV curve provide similar but not completely overlapping information; 3) SGaw and SBNT yield different (or less specific) information than the other tests; and 4) effects of cigarette smoking identified by productive cough are different from those identified by other tests.

Adult↗
PubMed1982

Response of individuals with reactive airway disease to sulfates and other atmospheric pollutants.

Severity of daytime and nighttime symptoms and medication requirements of 34 asthmatic volunteers were correlated to pollutant-pollen levels and to meteorologic characteristics continuously recorded over an eight-month period. Results of this longitudinal study suggest that as many as 9% of asthmatics may be sensitive to levels of sulfate in the ambient air and that reduction of sulfate levels to below 10 microgram/ml3 would significantly reduce tha frequency and severity of symptoms and needs for medication in these individuals.

Adolescent↗
PubMed1981

Mortality in persons with multiple sclerosis in the Seattle and Los Angeles areas.

Case-mortality and survival rates of more than 2,000 prevalent cases of multiple sclerosis (MS) residing in either Los Angeles County, California, or King and Pierce Counties, Washington, and followed up for 105 months, are reported. Case-mortality at the end 105 months was 16.9% of the total group. All age and sex groups had a lower survival rate than the US general population; this difference was especially pronounced in the high-disability groups. There was a trend toward higher case-mortality in high-disability Los Angeles County patients when compared with high-disability patients from King and Pierce Counties.

Adolescent↗
PubMed1981

Relationship between measles HI titers and an MS susceptibility gene.

Recently published studies of formal linkage analyses strongly suggest that a multiple sclerosis susceptibility (MSS) gene is linked to the HLA region of the sixth chromosome. The objective of this analysis was to investigate whether or not the gene has any demonstrable relationship to the immune status with regard to measles within members of multiple-case MS families. Family members were HLA-typed, and levels of antibodies to measles were determined using the hemagglutination inhibition assay. Since a specific, HLA-defined haplotype within each family is presumably a marker for the MSS gene, family members were characterized as either carrying [(+) controls] or not carrying [(-) controls] the MSS gene by the presence of this specific haplotype. Twenty families were entered into the analyses. Results revealed that the mean titer to measles was not different between (+) and (-) controls, and that MS cases had significantly higher titers than both control groups combined.

Age Factors↗
PubMed1981

Two populations with multiple sclerosis. Clinical and demographic characteristics.

Cross-sectional data from 1,793 cases of definite or probable multiple sclerosis (MS) identified in an extensive population survey in King and Pierce (K-P) Counties, Washington and Los Angeles (LA) County, California, were analyzed. Compared to the U.S. population as a whole, patients were more likely to be divorced and to have more years of schooling. The prevalence of MS was higher for females, and for northern-born, regardless of sex. Reconstructed age-, sex-specific incidence rate estimates for natives of the two areas showed a much higher peak annual incidence occurring in an older age group in K-P than in LA. Earliest symptoms in both areas were numbness in the legs, double vision, and loss of vision in one or both eyes. Weakness in arms, speech difficulties, and urinary incontinence tended to be late symptoms. The overall assessment of disability levels showed more than half of the patients to be fully ambulatory at the time of the first interview, with a somewhat higher proportion of each sex severely disabled in California. The ages of onset tended to be younger in LA than in K-P. The earlier onset of disease and the higher proportion of patients with high disability in Los Angeles County suggest that the course of disease is more malignant in this low-prevalence area.

Adolescent↗
PubMed1981

Similar levels of immune complexes in cases of multiple sclerosis and their unaffected relatives.

To investigate the possible effect of the hypothetical multiple sclerosis susceptibility (MSS) gene on circulating immune complexes, we employed a sensitive assay to test for the presence of immune complexes in sera of MS patients and unaffected relatives classified by the presence/absence of HLA-defined markers for the MSS gene. We found no significant differences between cases and relatives. The results suggest that elevated immune complex levels in MS patients' sera reported by others may not be unique to MS cases, but may represent instead a familial phenomenon. We also report a possible association between the A3 + B7 haplotype and increased immune complexes.

Antigen-Antibody Complex↗
PubMed1981

Epidemiology of gastric cancer in Chile: I - Case-control study.

The results of a case-control study of stomach cancer carried out with the collaboration of 7 participating hospitals in Santiago, Chile are reported. Patients attending gastroscopy clinics were interviewed before or after gastroscopy. The diagnosis was unknown to either the patient or the interviewer at the time of interview. 360 stomach cancer cases were subsequently matched to non-cancer patients selected from the pool interviewed at the same time as the cases. Study findings show: 1) longer-term residence in high-risk areas in early life by cases than controls; 2) an association between stomach cancer and a prior occupation in agriculture. In a subgroup of 98 cases for whom histologic classification was available, the association with residence in early life in a high-risk area was seen only for cases with intestinal-type stomach cancer.

Adult↗
PubMed1981

Epidemiology of gastric cancer in Chile: II - Nitrate exposures and stomach cancer frequency.

Nitrate levels in urine and nitrite levels in saliva were determined in school children 11-13 years of age in 2 areas of high stomach cancer mortality located in central Chile and in 2 areas of low stomach cancer mortality located at the extremes of Chile. Levels of both nitrates and nitrites were concurrently determined in selected vegetables obtained in these 4 study areas. Levels of nitrates were significantly higher in the urine of schoolchildren and in vegetables obtained from the northern low-risk area. Levels of nitrites were similar in saliva specimens from all 4 areas, but levels in vegetables were inconsistent. These results are apparently incompatible with the hypothesis of a high nitrate intake in areas of high stomach cancer incidence compared to areas of low incidence. This paradoxical finding suggests that cofactors may be involved in the pathopoiesis of stomach cancer that promote or inhibit the transformation of dietary nitrates to nitrosamines. The soil in the high-risk areas is primarily of volcanic origin, which is reported to be low in levels of selenium. On the other hand, residents of Antofagasta, the northern low-risk area, are known to be exposed to high levels of arsenic. It is possible that the diet of residents of the high incidence area which may be deficient in selenium may enhance promotion of nitrates to nitrosamines as has been reported in the literature, or conversely, that high levels of arsenic or other factors in the diet of individuals in Antofagasta may play a protective role. Other factors may be responsible for the low rate observed in the southern low-risk area.

Adolescent↗
PubMed1981

Multiple sclerosis and multiple moves: an etiologic hypothesis.

A case-control study of the number of childhood changes in residence of multiple sclerosis patients showed that cases had made significantly more moves than had controls. This difference may reflect a greater opportunity for exposure to a rare environmental agent or to multiple closely related agents.

Adolescent↗
PubMed1981

A survey diagnostic tool for senile dementia.

To validate a senile dementia survey diagnostic tool, 195 individuals aged 61-91 and referred by their physicians as normal or mildly demented were examined. The etiologic diagnosis used as criterion was the consensus of two experienced neurologists, assisted by clinical and laboratory data from referring physicians and by neuropsychologic evaluation of questionably affected persons. Agreement between the neurologists was high, as indicated by a weighted Kappa coefficient of 0.97 (95% confidence interval (Cl) (0.94, 1.00)). Agreement between the instrument and criterion diagnosis was also excellent (kappa w = 0.93; 95% Cl (0.88, 0.98)). Used alone as a screening diagnostic tool, the cognitive function portion of the instrument was much more sensitive (0.929) than previously used brief tests and was acceptably specific (0.800). Because normals complete this cognitive test in 15-20 minutes, it should be a major advance in population-based studies of senile dementia and normal aging.

Activities of Daily Living↗