Virginia A. Clark

Effects of various factors on systolic and diastolic blood pressure in the Los Angeles heart study

Abstract Higher systolic blood pressures were found among similar age groups measured in 1962 compared to those found in 1950 in the Los Angeles Heart Study. Analyses were performed to insure that these differences were real and not due to measurement differences or to self selection. Covariance analyses indicated that higher blood pressures occurred among subjects who reported that they had not eaten for 2 hr or more or for 5 hr or more prior to examination as well as among non-smokers, alcohol users, and non-salt adders. The magnitude of the differences associated with these factors is probably not of clinical significance. None of these factors explain the existing differences in blood pressures between these two examination periods. Thus, the differences observed are consistent with the hypothesis of a healthier population, age for age, entering the study in 1950 compared to the survivors examined in 1962.

Onset symptoms as predictors of mortality and disability in multiple sclerosis

Abstract– 941 cases of definite/probable multiple sclerosis living in Los Angeles County, California and King and Pierce Counties, Washington in 1970 who had onset between 1960 and 1969 were followed for mortality and disability through 1980. Early age of onset and residence in Washington State were predictors of less rapid and severe subsequent course. Coordination symptoms at onset were prognostic of rapid progression to disability and/or early death, whereas early motor weakness was significantly predictive only for disability. The presence of sensory symptoms in addition to motor and/or coordination symptoms at onset, however, indicated a better prognosis than coordination and/or motor symptoms alone. This observation and the results of regression analyses indicated that specific groupings of symptoms at onset were more important for predicting course than the number of symptoms present at onset.

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.

Two populations with multiple sclerosis

SummaryCross-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.ZusammenfassungEs wurden Durchschnittsdaten von 1793 Fällen definitiver und wahrscheinlicher Multipler Sklerose (MS) analysiert, die in umfangreichen Bevölkerungserhebungen identifiziert wurden, in den Landkreisen King und Pierce (K-P) in Washington und in dem Landkreis Los Angeles (LA). Verglichen mit der Gesamtbevölkerung der Vereinigten Staaten, waren die Patienten häufiger geschieden und hatten mehr Jahre Schulung. Das Auftreten von MS war häufiger bei weiblichen Personen und bei solchen, die im Norden geboren waren, ungeachtet des Geschlechts. Die Schätzungen der Rate der rekonstruierten alters- und geschlechtsspezifischen Fälle für die Einwohner der zwei Gebiete zeigt einen viel höheren Höchstwert von jährlichem Fallauftreten bei den älteren Altersgruppen in K-P als in LA. Erste Symptome in beiden Gegenden waren Gefühllosigkeit in den Beinen, Doppelsichtigkeit und Verlust des Sehvermögens auf einem oder beiden Augen. Schwäche in den Armen, Sprachschwierigkeiten und Harnfluß waren mehr spätere Symptome. Die Gesamtbewertung der Behinderungsstadien zeigte, daß mehr als die Hälfte der Patienten zur Zeit des ersten Interviews völlig ambulant waren, mit einem etwas höheren Anteil an schwer behinderten bei Personen von beiderlei Geschlecht in Kalifornien. Das Alter bei Beginn neigte in LA jünger zu sein als in K-P. Das frühere Anfangsalter der Krankheit und der höhere Anteil von Patienten mit schwerer Behinderung in dem Landkreis Los Angeles weist auf einen bösartigeren Verlauf in diesem Gebiet mit geringer Verbreitung.

Choice of Levels in Polynomial Regression with One or Two Variables

Suggested levels for the independent variables are tabled for polynomial regression in one variable and for two particular polynomial regressions in two independent variables when the minimum number of distinct levels is used. The criterion used for finding these levels was restricted minimization of the generalized variance. An explanation of the usefulness of this criterion is given, and a computational method is outlined to find levels for other regression equations using this criterion.

Role of Heat in Multiple Sclerosis Symptoms in a High- and a Low-Prevalence Area

A significantly higher proportion of Los Angeles County (State of California, USA) multiple sclerosis patient than of King-Pierce Counties (State of Washington, USA) patients, interviewed as part of a