Epidemiology of kidney stones in Iceland: a population-based study.

OBJECTIVE: The prevalence of kidney stones varies greatly between ethnic groups and geographic locations, ranging from 8% to 19% in males and from 3% to 5% in females in Western countries. The aim of this study was to examine the epidemiology of kidney stones in Iceland. MATERIAL AND METHODS: Data were derived from the Reykjavik Study, a population-based cohort study carried out between 1967 and 1991. All subjects answered a thorough questionnaire concerning their medical history at each visit. The lifetime prevalence of kidney stones was calculated based on the answer to the question "Have you ever been diagnosed with a kidney stone?" at each person's first visit. Incidence was calculated based on answers from subjects who had made two or more visits. Prevalence and incidence were age-standardized to the truncated world population. Family history of kidney stones was also evaluated. RESULTS: A total of 9039 men aged 33-80 years and 9619 women aged 33-81 years participated. Of these, 423 males and 307 females had a history of kidney stones (p=0.001). Prevalence increased significantly with age for both genders. Men aged 30-34 years had a prevalence of 2.9%, compared to 8.8% for those aged 65-69 years, whereas corresponding values for women were 2.5% and 5.0%. The age-standardized prevalence for the 30-79 years age group was 4.3% for men and 3.0% for women. No significant increase in prevalence was observed over time. The incidence was 562 per 100 000 per year among men and increased significantly with age. The incidence among women was 197 per 100 000 per year and did not differ between age groups. A family history of nephrolithiasis was present in 25% of subjects with a history of kidney stones, and in 4% of those without. CONCLUSIONS: The incidence and prevalence of kidney stones in Icelandic women are similar to those that have been reported in other Western countries. The prevalence among men is lower that in neighboring countries but the incidence is similar. A strong family history of kidney stones suggests a genetic predisposition.

[The health risk associated with smoking has been seriously underestimated. The Reykjavik Study]. / Skadleg áhrif reykinga á heilsufar hafa verid verulega vanmetin. Nidurstödur úr hóprannsóknum Hjartaverndar.

OBJECTIVE: To assess the risk for coronary heart disease, myocardial infarction, cancer deaths, and all deaths associated with different smoking categories as determined by smoking status at a baseline examination only and at a baseline with reexamination 15-19 years later (persistent smokers). MATERIAL AND METHODS: The participants were a random sample of 2930 men and 3084 women aged 34-61 years (when selected in 1967) invited for various standardized examinations under two periods, 1967-1972 and 1979-1991 and followed-up until the end of year 2001. The main outcome measures were clinical coronary heart disease, myocardial infarction, cancer deaths, and all deaths. Risk was calculated for each smoking category as determined by two assessments of smoking habits and also compared with the risk as determined by one baseline examination only. RESULTS: Mean follow-up for men was 26 years (SD 9 years). For women the mean follow-up was 28 years (SD 7 years). There were substantial differences in hazard ratios (HR) and median lifetime in smoking groups as determined by one or two examinations. In men the greatest difference in hazard ratios was for cancer deaths (one examination: 2.80, two: 3.83) in women for total deaths (3.02 vs. 3.7). Loss of median lifetime was greatest in "heavy" cigarette smoking men (one examination: eight years; two examinations: 13 years), in women the corresponding figures were nine and 10 years, in "light" cigarette smokers, the figures for men were four and nine years, and for women four and six years. CONCLUSIONS: Middle-aged men smoking one or more packets of cigarettes per day shorten their life expectancy by 13 years and middle-aged women by 10 years. Only one baseline determination of smoking status with subsequent follow-up underestimates the health risk associated with smoking by 15-40% at least in populations where smoking prevalence is declining.

Hypertension control as predictor of mortality in treated men and women, followed for up to 30 years.

PURPOSE: To examine the prognosis of treated, hypertensive individuals in the Reykjavik Study. METHODS: A population-based longitudinal study of 9328 men and 10 062 women. Subjects were included in the study during the period 1967-1996. Two groups of treated, hypertensive subjects were defined at baseline: with controlled blood pressure and with uncontrolled blood pressure. Main outcome measures were cardiovascular disease (CVD) mortality and all-cause mortality. RESULTS: Of the hypertensive men 24.8% were treated, and of those 38.3% were controlled, and of the hypertensive women 45.3% were treated, and of those 52.7% were controlled. Comparing treated and uncontrolled (systolic blood pressure (SBP) > or =160 mmHg and/or diastolic blood pressure (DBP) > or =95 mmHg) versus treated and controlled hypertensive subjects, followed for up to 30 years, the uncontrolled men and women were at significantly higher risk of CVD mortality, hazard ratio (HR) = 1.47 (95% confidence interval (CI): 1.06-2.02) and HR 1.70 (CI: 1.23-2.36), respectively, showing the benefit of hypertension control. The risk of all-cause mortality was increased for treated, uncontrolled men and women, compared with those who were treated and controlled, but did not reach significance. When analyzing blood pressure as a continuous variable among treated, hypertensive subjects, SBP was a better predictor than DBP of CVD mortality and all-cause mortality in women. This was not the case in men. CONCLUSIONS: Control of blood pressure among hypertensive-treated subjects at baseline was associated with a lower risk of CVD mortality during follow-up. SBP was the single best predictor of CVD mortality and all-cause mortality in treated women. The uncontrolled women were at a higher risk than the uncontrolled men.

[Coronary risk factors among men and women in Iceland. Results from the Reykjavik Study 1967-1985. 1992]. / Ahaettuthaettir kransaedasjúkdóms medal karla og kvenna á Islandi. Nidurstödur úr hóprannsókn Hjartaverndar 1967-1985.

The Reykjavík Study 1967-1985: Risk factors for coronary heart disease mortality have been investigated in a prospective study of 8001 randomly selected Icelandic men and 8468 women. The men were aged 34-64 and the women 34-76 at the time of their first examination. After followup from 2-17 years 1140 (14.2%) of the men and 537 (6.3%) of the women had died. Coronary heart disease accounted for 43% of the mortality among the men, cancer 27% and cerebrovascular disease 7%. This distribution is in contrast to what was found among the women. Coronary heart disease accounted for 19.4% of the mortality, cancer 42.3% while the relative contribution of cerebrovascular mortality was similar. The effects of various factors were assessed simultaneously with multivariate survival analysis using the Cox's proportional hazard model. Age, serum total cholesterol, triglycerides, smoking and systolic blood pressure were all significant independent risk factors for coronary heart disease mortality in both sexes. Fasting blood sugar was of borderline significance, reaching significance among men, but not among women. However, since the women have much lower risk of dying from coronary heart disease than the men the absolute risk associated with each of the risk factors is much lower in the women.

The absolute risk of recurrent myocardial infarction is similar amongst both sexes: MONICA Iceland Study 1981-1999.

BACKGROUND: To do a gender comparison of absolute risk of recurrent myocardial infarction (MI). DESIGN: Registration of all first and second MI amongst Icelandic males and females 1981-1999. METHODS: The whole of Icelandic population, 40-74 years of age. RESULTS: The mean recurrence rate (second attack) for men was 45.7/1000 MI survivors/year and for women 39.0/1000 per year. The male/female (M/F) ratio was 1.17, 95% confidence interval 1.00-1.37, P = 0.05 and did not change significantly with age. The M/F ratio for first MI in comparison was two to seven, lowest in the oldest group. The recurrence rate decreased significantly and similarly in both sexes during the observation period. CONCLUSION: The absolute risk of MI is closely similar amongst both sexes and has decreased similarly suggesting that the same kind of secondary intervention is effective amongst both sexes in a general population.

Erythrocyte sedimentation rate, an independent predictor of coronary heart disease in men and women: The Reykjavik Study.

The relation between erythrocyte sedimentation rate (ESR) and risk of developing coronary heart disease (CHD) or fatal cerebrovascular accident was assessed in a cohort of 7,988 men and 8,685 women who participated in The Reykjavik Study (Iceland). Cardiovascular risk assessment was based on characteristics at baseline, from 1967 to 1996. During an average follow-up of 19 and 20 years, 2,092 men and 801 women, respectively, developed CHD, and 251 men and 178 women died from cerebrovascular accident. For men, the fully adjusted increase in risk of developing CHD predicted by the top compared with the bottom quintile of ESR was 57% (hazard ratio = 1.57, 95% confidence interval: 1.38, 1.78; p < 0.001); for women, risk was increased by 49% (hazard ratio = 1.49, 95% confidence interval: 1.16, 1.90; p < 0.001). The increased risk after baseline ESR measurement was stable for up to 25 years for men and 20 years for women. The fully adjusted risk of death due to stroke predicted by increasing the ln(ESR + 1) by one standard deviation was increased by 15% for men (p = 0.06) and 16% for women (p = 0.08). In conclusion, ESR is a long-term independent predictor of CHD in both men and women. These findings support the evidence of an inflammatory process in atherosclerosis.

[Changes in smoking habits in the last thirty years in middle-aged Icelanders and their causes - Results from population surveys of the Icelandic Heart Association.].

OBJECTIVE: During the last thirty years the Research Clinic of the Icelandic Heart Association has been engaged in several extensive cardiovascular population surveys. Smoking habits have been assessed by a questionnaire and the purpose of the present study is to describe the changes in smoking habits during the period 1967-2001, their causes and the reliability of the information gathered. MATERIAL AND METHODS: The subjects were participants in four population surveys: The Reykjavik Study 1967-1996, Survey of "Young People" 1973-1974 and 1983-1985, MONICA Risk Factor Surveys 1983, 1988-1989 and 1993-1994 and the "Reykjavik Offspring Study" 1997-2001. The age of participants was 30-88 years and 26,311 examinations of males and 26,222 of females were performed, a number of individuals attending more often than once. A standardized smoking questionnaire was used and the reliability was assessed. RESULTS: Smoking prevalence decreased substantially in both sexes during the study period. In the youngest male group the prevalence decreased from 65% to 42%, but in the oldest from 45% to 19%, while in the youngest female group the decrease was from 50% to 35% but in the oldest age group from 30% to 20%. The decrease in smoking was almost exclusively in the category of "light smokers" (i.e. 1-14 cigarettes a day or pipe/cigar smoker). The main reasons for quitting smoking were concerns about health and symptoms associated with smoking and the cost. The cost had greater weight at the beginning of the period than during the latter part but health concerns seem to be increasingly important. Compared to other countries smoking prevalence in Icelandic males is low but high in females. CONCLUSION: During the last three decades smoking prevalence in Icelanders 30 years and older has decreased substantially. The main reasons for quitting smoking are health concerns and cost. Continued information about the deleterious effects of smoking as well as increase in the price of tobacco is likely to reduce further the smoking prevalence.

Prevalence and progression of CRF in Iceland: a population-based study.

BACKGROUND: The prevalence of end-stage renal disease (ESRD) is lower in Europe than in the United States. The purpose of this study was to examine whether this difference results from a lower prevalence or slower progression of chronic renal failure (CRF) in a European cohort. METHODS: We studied 18,912 subjects (9,773 women, 9,139 men) aged 33 to 81 years who participated in the Reykjavik Study between 1967 and 1991. Subjects with serum creatinine (SCr) levels of 1.7 mg/dL (150 micromol/L) or greater were considered to have CRF. We determined the crude prevalence of CRF, as well as age-standardized prevalence for 5-year age groups, in individuals aged 30 to 79 years. Progression of CRF was defined as a decrease in estimated glomerular filtration rate greater than 1 mL/min/1.73 m2/y. RESULTS: Of 49 individuals who had an SCr of 1.7 mg/dL (150 micromol/L) or greater at entry, 41 individuals (26 men, 15 women) had a persistent elevation in SCr levels. Thirty-four individuals had mild CRF (SCr, 1.7 to 2.8 mg/dL [150 to 250 micromol/L]), 6 individuals had moderate CRF (SCr, 2.8 to 5.6 mg/dL [250 to 500 micromol/L]), and 1 individual had ESRD. The crude prevalence of CRF was 0.22% (220/100,000); 0.15% among women and 0.28% among men. The age-standardized prevalence was 0.23% (95% confidence interval [CI], 0.04 to 0.42) for women and 0.42% (95% CI, 0.18 to 0.66) for men. Eighty-five percent of patients with CRF were 50 years or older. Twenty-seven subjects had progressive renal failure, 17 of whom progressed to ESRD during a median of 7 years (range, 3 to 21 years). CONCLUSION: The prevalence of CRF is markedly lower in Iceland than in the United States. Furthermore, 27% of subjects did not show progression of their renal failure. These factors may explain in part the difference in ESRD prevalence between European countries and the United States.

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.

Increased total mortality and cancer mortality in men with Dupuytren's disease: a 15-year follow-up study.

The aim of the present study was to evaluate the mortality rate and causes of death of individuals with Dupuytren's disease. In 1981/82, as part of The Reykjavík Study, a general health survey, 1297 males were examined for clinical signs of Dupuytren's disease. Based on the clinical evaluation the participants were classified into three groups: (1) those with no signs of Dupuytren's disease were referred to as the reference cohort; (2) those with palpable nodules in the palmar fascia were classified as having stage 1; and (3) those who had contracted fingers or had been operated on due to contractures were classified as having stage 2 of Dupuytren's disease. In 1997, after a 15- year follow-up period, the mortality rate and causes of death were investigated in relation to the clinical findings from 1981/82. Information about causes of death were obtained from the National Icelandic Death Registry and the Icelandic Cancer Registry. During the follow-up period, 21.5% (225/1048) of the reference cohort were deceased compared to 29.9% (55/184) of those with stage 1 and 47.7% (31/65) of those with stage 2 of Dupuytren's disease. When adjusted for age, smoking habits and other possible confounders, individuals with stage 2 of the disease showed increased total mortality [hazard ratio (HR) = 1.6; 95% CI 1.1-2.4]. Cancer deaths were increased (HR = 1.9; CI 1.0-3.6). In contrast, participants with stage 1 of Dupuytren's disease did not show increased mortality. A moderate but non-significant increase in cancer incidence was observed among individuals with stage 2 of Dupuytren's disease (HR = 1.5; 95% CI 0.9-2.4, P = 0.15). The study showed increased total mortality of individuals with Dupuytren's disease stage 2, where 42% of the excess in mortality could be attributed to cancer deaths.

Declining coronary heart disease mortality in Iceland: contribution by incidence, recurrence and case fatality rate.

OBJECTIVE: To analyse to what extent the recent decline in coronary heart disease mortality in Iceland is due to changes in incidence, recurrence and case fatality rates. DESIGN: A countrywide registration of myocardial infarction (MI) in people aged 25-74 was performed in Iceland during 1981-1999 according to the MONICA protocol. Possible cases were found by review of all hospital discharge records, autopsy records and death certificates. RESULTS: MI death rate declined by 63% in males and 51% in females, most in the youngest age groups in men (86%) and least in the oldest (49%). In women there was not a significant difference in age groups. Overall the age-adjusted reduction in MI death rate was 55.4% in both sexes combined; of this 23.1% was due to incidence reduction, 22.8% to recurrence reduction and 11.6% to case fatality reduction. In the youngest age groups the decline in incidence contributed most to the decline in MI death rate (62% in men and 71% in women), but thereafter the decline in case fatality in men. In the older age groups decline in recurrence rate has greater weight. CONCLUSION: The recent decline in MI mortality under the age of 75 years in Iceland is due to reduction in incidence and recurrence rate by about 40% each and to reduction in case fatality by 20%.

[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.