Biomedical subjects

Helgi Sigvaldason

Publications and source records attributed to Helgi Sigvaldason.

22 records · Page 2Linked to original sources

PubMed2002

Seasonal affective disorders: relevance of Icelandic and Icelandic-Canadian evidence to etiologic hypotheses.

OBJECTIVE: This study tests the suggestion of earlier studies concerning the importance of genetic factors in the etiology of winter seasonal affective disorders (SADs) and subsyndromal winter SAD (S-SAD). METHOD: Two study populations of Winnipeg, Manitoba residents were canvassed: 250 adults of wholly Icelandic descent and 1000 adults of non-Icelandic descent. We distributed the Seasonal Pattern Assessment Questionnaire by mail to these 2 populations, yielding 204 and 449 valid responses, respectively. RESULTS: Rates of SAD and S-SAD proved markedly lower in the Icelandic population than those in the non-Icelandic population. CONCLUSIONS: These differences seem unexplained by differences in ambient light or climate, thus indicating that genetic factors contribute to the expression of SADs. Compared with earlier findings from a group of adults of wholly Icelandic descent living in nearby rural Manitoba, the etiologic importance of as-yet-undetermined environmental factors unrelated to latitude or ambient light is also indicated.

Adolescent↗

PubMed2002

Do lipids, blood pressure, diabetes, and smoking confer equal risk of myocardial infarction in women as in men? The Reykjavik Study.

BACKGROUND: Studies on coronary risk factors in men and women are mainly based on mortality data and few compare results of both sexes with consistent study design and diagnostic criteria. This study assesses the major risk factors for coronary events in men and women from the Reykjavik Study. DESIGN: Within a prospective, population-based cohort study individuals without history of myocardial infarction were identified and the relative risk of baseline variables was assessed in relation to verified myocardial infarction or coronary death during follow-up. METHODS: Of the 9681 women and 8888 men who attended risk assessment from 1967-1991, with follow-up period of up to 28 years, 706 women and 1700 men suffered a non-fatal myocardial infarction or coronary death. RESULTS: Serum cholesterol was a significant risk factor for both sexes, with hazard ratios (HR) decreasing with age. Systolic blood pressure was a stronger risk factor for women as was ECG-confirmed left ventricular hypertrophy (women HR 2.89, 95% confidence interval [CI] 1.67-5.01; men HR 1.11 [CI 0.86-1.43]). Fasting blood glucose > or =6.7 mmol/L identified significantly higher risk for women (HR 2.65) than men (HR 2.08) as did self-reported diabetes. Triglyceride risk was significantly higher for women and decreased significantly with age. Smoking increased risk two- to five-fold, increasing with dose, for women, which was significantly higher than the doubling in risk for men. CONCLUSIONS: This large study of the major risk factors compared between the sexes demonstrates similar relative risk of myocardial infarction associated with cholesterol for both sexes, however, the relative risk is higher in women for many other risk factors such as smoking, diabetes, elevated triglycerides and left ventricular hypertrophy.

Adult↗

PubMed2002

[Carcinoma of the colon in Iceland 1955-1989. An investigation of survival according to various pathological parameters.].

OBJECTIVE: The purpose of this study was to estimate various pathological parameters of colon carcinoma over a 35 year time period and evaluate their effect on survival of the patients. MATERIAL AND METHODS: All pathological specimens from patients diagnosed with colon carcinoma in Iceland in the period 1955 to 1989 were re-evaluated in order to determine the following pathological parameters: Tumour size, gross appearance, tissue type, grade, Dukes stage, lymphatic and/or blood vessel invasion, lateral margin involvement, Jass-group of tumour, peritumoural lymphocytic infiltrate, limitation of tumour growth to bowel wall, lymph node metastases, invasive tumour margin and colloid component in adenocarcinoma. Also the following parameters were determined in every case: Age at diagnosis, sex, year of diagnosis and tumour location within the bowel. All these parameters were evaluated with respect to survival of the patients. RESULTS: According to the Icelandic Cancer Registry 1265 patients were diagnosed with colon cancer in Iceland in the period under investigation. After re-evaluation 1205 patients fulfilled the criteria of a primary colon cancer and of those we were able to re-evaluate specimens from 1109 patients to determine histopathological parameters. In a univariable analysis most of the parameters investigated proved significant with respect to survival, except sex, anatomical location of tumour within the bowel, and the proportion of colloid component of tumour. In a multivariable analysis the age at diagnosis proved important as well as the year/period of diagnosis. The following pathological parameters evaluated had a significant prognostic input with regard to survival: Tumour grade, Dukes stage, number of lymph nodes with metastases, peritumoral lymphocytic infiltrate, lateral margin involvement in the surgical specimen and invasive growth pattern of tumour margin. CONCLUSIONS: Many pathological parameters are important in regard with prognostic evaluation of patients diagnosed with colon cancer. We suggest that pathologists should include in their surgical pathology specimen reports of colon cancer, in addition to traditional parameters, an evaluation of peritumoral lymphocytic infiltrate, lateral margin involvement with tumour and the growth pattern of tumour at the invasive margin.

English Abstract↗

PubMed2002

[The relationship between educational level, physical activity and mortality.].

OBJECTIVES: The relationship between educational level and mortality is well known. This has been shown in the Reykjavik Study and was only partly accounted for by unequal distribution of known risk factors. The objective of the present study was to explore the relationship between educational level and physical activity and whether that relationship could partly explain differences in mortality. MATERIAL AND METHODS: This is a part of the Reykjavik Study. Presented is data from 18,912 participants, divided into four groups by educational level. Physical activity was assessed by questionnaire. The relationship between physical activity and educational level was assessed by logistic regression and between mortality and educational level by Cox regression analysis. Adjustments were made for age, year of examination, known risk factors (serum lipids, blood pressure, height, weight, smoking, use of anti-hyertensive drugs and 90 min glucose tolerance) and physical activity. RESULTS: There was a positive relationship between physical activity and educational level (p<0.001). By adding adjustments for physical activity to a multiple regression analysis containing other known risk factors the relationship between total mortality and educational level was reduced. For highest versus lowest educational group hazard ratio was elevated from 0.77 to 0.80 for men and from 0.91 to 0.93 for women. Same trend existed for cardiovascular mortality and to a less extent for cancer mortality. CONCLUSION: The association between educational level and mortality can be partly explained by differences in leisure-time physical activity. In spite of adjustments for known risk factors and physical activity there remains a statistically significant relationship between educational level and mortality.

English Abstract↗