Oral contraceptives, pregnancy, and endogenous oestrogen in gall stone disease--a case-control study

Oral contraceptive use and benign gallbladder disease; revisited

An analysis is described of 482 women with benign gallbladder disease (surgically confirmed in 407) identified in the Oxford Family Planning Association contraceptive study. There was no significant overall association between oral contraceptive use and gallbladder disease (relative risk ever use to never use 1.1, 95% confidence interval 0.9 to 1.3). Likewise, duration of oral contraceptive use had no significant effect (relative risk 97 or more months use to never use 1.1, 95% confidence interval 0.8 to 1.5). There was no indication of any interaction between oral contraceptive use and body mass index or oral contraceptive use and age in the production of disease. It is concluded that it is unlikely that oral contraceptives are of either clinical or public health significance in relation to the occurrence of gallbladder disease.

[Dietetic influences on the formation and prevention of cholesterol gallstones]

Dietary factors have long been considered to influence the formation of cholesterol gallstones. A number of clinical and epidemiological studies have demonstrated, although with inconsistent results, the possible impact of dietary factors such as high energy intake, high intake of cholesterol and fat (especially polyunsaturated fatty acids), high intake of refined carbohydrates, and low intake of dietary fiber. However, the obvious increase in the prevalence of gallstones in Western countries after the second world war is thought to underline a role of lifestyle and dietary factors. The following review summarizes current information concerning dietary risk factors and their impact on gallstone formation and prevention.

Cholelithiasis in the gravid Hispanic population

Ultrasound examinations were performed to determine the prevalence of cholelithiasis in 585 pregnant Hispanic patients. The ultrasound findings were correlated with age and country of birth. The overall prevalence of gallstones was 5.3%. This is not statistically different from the prevalence of gallstones in age-matched groups from previously published studies not selected for country of birth or ethnic background. We found no statistically significant different in prevalence rates for gallstones between Mexican-born and non-Mexican-born pregnant Hispanic women in the 20-year to 49-year age group. Unlike prior studies, this study does not support the use of increased ultrasound examination for cholelithiasis in a pregnant Hispanic population.

Cigarette smoking and parity as risk factors for the development of symptomatic gall bladder disease in women: results of the Royal College of General Practitioners' oral contraception study

The effects of cigarette smoking and parity on the development of symptomatic gall bladder disease remain controversial. These relations have been examined in a cohort of 46,000 women followed for up to 19 years during the Royal College of General Practitioners' (RCGP) oral contraception study. During follow up, 1087 women were recorded as experiencing their first ever episode of symptomatic cholelithiasis (International Classification of Diseases, 8th revision (ICD-8) 574) or cholecystitis (ICD-8 575). Smokers were more likely to develop symptomatic gall bladder disease than non-smokers (relative risk 1.19; 95% confidence intervals (95% CI) 1.06 to 1.34) and there was a significant trend with the number of cigarettes smoked daily (test for trend chi 2 = 7.58, p < 0.01). This relation was most apparent among never users of oral contraceptives, although similar trends were found among current and former users. A significant direct relation between symptomatic gall bladder disease and parity was also found (test for trend chi 2 = 21.89, p < 0.001). When all were examined together a trend of increasing risk with lower social class was also found (test for trend chi 2 = 5.72, p = 0.02). Current users of oral contraceptives had a moderately increased risk of symptomatic gall bladder disease (relative risk 1.15; 95% CI 0.99 to 1.34), unlike former users (relative risk 1.03; 95% CI 0.90 to 1.18). These results suggest that smoking and parity are important risk factors for the development of symptomatic gall bladder disease in women.

Cytometric study of the female Syrian hamster gallbladder epithelium following sex steroid administration

This report is a cytometric study of the female Syrian hamster gallbladder epithelium following 1-, 2-, and 3-month administration of female sex steroids. Nulliparous, multiparous, young, old and pregnant hamsters were used in this study. A 1 month treatment with estrogen alone significantly increases the nuclear volume of the gallbladder epithelial cells, while E + P treatment significantly affects the nuclear volume only after a 2 month treatment. On the other hand, E + P and P treatments significantly increase the cell volumes as compared to the E-treated groups, this effect is most striking following the 1 month period. Prolonged sex steroid treatment (2 and 3 month) does not appear to influence the gallbladder epithelial cell and nuclear volumes as dramatically as that observed following the 1 month treatment. The nulliparous, progesterone-treated hamsters appear to have a greater cytoplasmic volume than the multiparous group and this is substantiated by the bulging apices and the luminal cellular excrescences observed with scanning and transmission electron microscopy. These observations are similar to those reported in ovariectomized hamsters (Gilloteaux et al., 1992). Further, the gallbladder epithelial cells and nuclei of the older female hamsters demonstrate an accentuated response to a 1 month sex steroid treatment as compared to the younger hamsters for the same treatment duration. These results enable us to hypothesize that changes induced by a short term sex steroid treatment participate in the gallstone nucleation process, while longer duration of the treatments contribute to progressive enlargement and accumulation of gallbladder calculi.

Oral contraceptives and the risk of gallbladder disease: a meta-analysis

OBJECTIVES

This study was designed to assess the risk of gallbladder disease due to oral contraceptive use by conducting a thorough literature review.

METHODS

Controlled epidemiologic studies published through March 1992 were systematically searched and evaluated. Of 25 studies (27 publications), 9 could stand the test of critical appraisal with respect to validity. Restriction to these studies was judged to circumvent publication bias at the same time.

RESULTS

Oral contraceptive use is associated with a slightly and transiently increased rate of gallbladder disease. The results of six selected studies in which asymptomatic women were screened for gallstones were strikingly similar. Pooling of these results yielded an odds ratio, for ever vs never oral contraceptive use, of 1.36. A dose-effect relationship was indicated, suggesting that modern low-dose oral contraceptives are safer than older formulas, but an effect cannot be excluded.

CONCLUSIONS

Considering the large efforts already devoted to this exposure-disease relationship, the probably weak effect, and the rapidly changing formulas of oral contraceptives, the authors suggest that the safety of new oral contraceptives be evaluated by studying bile saturation and biliary function rather than by waiting for gallbladder disease to develop.

Parity and cancers of the gall bladder and the extrahepatic bile ducts

The relation of parity and age at first birth to cancers of the gall bladder and extrahepatic bile ducts in women was studied using a database generated by linking 2 Swedish national registries; the Fertility Registry and the Cancer Registry. Among women born between 1925 and 1960, 257 cases of gall-bladder cancer recorded in the Cancer Registry between 1958 and 1984 were compared with 1,285 controls, age-matched to cases in a 5:1 ratio. In addition, 60 cases of extrahepatic-bile-duct cancer were matched with 300 controls. There was a positive association between number of live births and risk of gall-bladder cancer (p 0.06), but simultaneous consideration of parity and age at first birth revealed a more complex picture. Parity increases the risk for cancer of the gall bladder when the first birth occurs before the age of about 25 years, whereas parity associated with first birth after the age of about 30 years is associated with reduced risk for the disease. Thus, among parous women there is a highly significant inverse association of age at first birth with risk for gall-bladder cancer after adjustment for number of live births. Variable levels of pregnancy estrogens according to maternal age and variable effects of parity on non-pregnancy estrogens by age, may explain the observed pattern. The results on extrahepatic-bile-duct cancer, parity and age at first birth did not indicate the existence of an association in either direction.

Oral contraceptives and non-contraceptive oestrogens in the risk of gallstone disease requiring surgery

STUDY OBJECTIVE

The aim was to investigate the relationship between oral contraceptives, non-contraceptive oestrogens, and the risk of gallstone disease requiring surgery.

DESIGN

This was a hospital based case-control study carried out between 1987 and 1990. Main outcome measures were frequency of consumption of oral contraceptives and non-contraceptive oestrogens, and the corresponding multivariate relative risk estimates and 95% confidence intervals (CI) in relation to various measures of use of the preparations.

SETTING

A network including major teaching and general hospitals in the greater Milan area, northern Italy.

SUBJECTS

Subjects were 235 women with gallstones requiring surgery and 538 controls admitted for acute diseases, other than digestive or hormonal diseases or those potentially influencing the use of female hormone preparations.

MAIN RESULTS

For oral contraceptives, the relative risk for ever use was 0.8 with 95% CI 0.4 to 1.5. With reference to duration of use, the multivariate relative risk was 1.0 for less than two and 0.5 for two or more years of use. The relative risk was 1.7 (95% CI 0.6 to 4.7) in women who had last used the pill less than five years before diagnosis, but declined to 0.4 (95% CI 0.2 to 1.0) in those who had stopped more than five years before. With reference to oestrogen replacement treatment, the relative risk for ever use was 1.9 (95% CI 1.0 to 3.1). The relative risk, however, was not related to duration of use, since it was 1.8 for less than two and 1.5 for two or more years of use. Relative risk was higher for women who had last used non-contraceptive oestrogens 10 or more years before diagnosis (2.4) than for shorter periods since last use (1.3).

CONCLUSIONS

On a clinical and public health scale, oral contraceptives and non-contraceptive oestrogens are unlikely to have an important influence in the aetiology of gallbladder disease.

Drug-induced gallbladder disease. Incidence, aetiology and management

A great variety of drugs is reported to induce gallbladder disease by various pathogenetic mechanisms. Early epidemiological studies indicated a doubled risk of gallbladder disease in women taking oral contraceptives. More recent studies, however, have failed to confirm those findings; these conflicting results might be explained by the different methods used to define gallbladder disease. It was shown that the lithogenic index of the bile is increased during intake of oral contraceptives. Estrogens cause hypersecretion of cholesterol in bile, due to increase in lipoprotein uptake by the hepatocyte. Progesterone inhibits acyl coenzyme A-cholesterol acyl transferase (ACAT) activity, causing delayed conversion of cholesterol to cholesterol esters. Of the lipid lowering drugs, only clofibrate has been shown to increase the risk for gallstone formation. The other fibric acid derivatives have similar properties, but clinical experience is not as extensive. They seem to be inhibitors of the ACAT enzyme system, thereby rendering bile more lithogenic. Conflicting epidemiological data exist regarding the induction of acute cholecystitis by thiazide diuretics. Ceftriaxone, a third-generation cephalosporin, is reported to induce biliary sludge in 25 to 45% of patients, an effect which is reversible after discontinuing the drug. The sludge is occasionally a clinical problem. It was clearly demonstrated that this sludge is caused by precipitation of the calcium salt of ceftriaxone excreted in the bile. Long term use of octreotide is complicated by gallstone formation in approximately 50% of patients after 1 year of therapy, due to gallbladder stasis. Hepatic artery infusion chemotherapy by implanted pump is shown to be associated with a very high risk of chemically induced cholecystitis. Prophylactic cholecystectomy at the time of pump implantation is therefore advocated. Some drugs, such as erythromcyin or ampicillin, are reported to cause hypersensitivity-induced cholecystitis. Furthermore, there are reports on the influence of cyclosporin, dapsone, anticoagulant treatment, and narcotic and anticholinergic medication in causing gallbladder disease.

The association of oral contraception with kidney cancer, colon cancer, gallbladder cancer (including extrahepatic bile duct cancer) and pituitary tumours

This paper reviews the evidence for a relationship between oral contraceptive use and certain neoplasms: cancers of the kidney, colon and gallbladder (including the extrahepatic bile ducts) and tumours (benign or malignant) of the pituitary. Special reference is made to controlled epidemiological studies, both case-control and cohort. There is no convincing evidence that oral contraceptive use is causally related, either negatively or positively, to any of the tumours studied.

Mechanisms of gallstone formation in women. Effects of exogenous estrogen (Premarin) and dietary cholesterol on hepatic lipid metabolism

Our aim was to define mechanisms whereby conjugated estrogens (Premarin, exogenous estrogen; Ayerst Laboratories, New York) increase the risk of developing cholesterol gallstones and to determine the role, if any, of dietary cholesterol. We studied gallbladder motor function, biliary lipid composition and secretion, cholesterol absorption, cholesterol synthesis and esterification by peripheral blood mononuclear cells, the clearance of chylomicron remnants, and bile acid kinetics in 29 anovulatory women. 13 were studied on both a low (443 +/- 119 mumol/d) and high (2,021 +/- 262 mumol/d) cholesterol diet. Premarin increased the lithogenic index of bile (P less than 0.05), increased biliary cholesterol secretion (P less than 0.005), lowered chenodeoxycholate (CDCA) pool (P less than 0.001) and synthesis (P less than 0.05), altered biliary bile acid composition [( CA + DCA]/CDCA increases, P less than 0.005), stimulated cholesterol esterification (P less than 0.03), and enhanced the clearance of chylomicron remnants (P = 0.07). Increases in dietary cholesterol stimulated the biliary secretion of cholesterol (P = 0.07), bile acid (P less than 0.05), phospholipid (P = 0.07), and as a result, did not alter lithogenic index. The reduction in CDCA pool and synthesis by Premarin was reversed by increasing dietary cholesterol. Off Premarin, only 24% of the increase in cholesterol entering the body in the diet was recovered as biliary cholesterol or newly synthesized bile acid. On Premarin, 68% of this increase in cholesterol was recovered as these biliary lipids. We conclude that Premarin increases biliary cholesterol by enhancing hepatic lipoprotein uptake and inhibiting bile acid synthesis. These actions of Premarin divert dietary cholesterol into bile.

The relationship between reproductive history and cholecystectomy in older women

We examined the relationship of reproductive history to cholecystectomy in a population-based sample of 1093 women aged 50 years and older. Number of pregnancies ranged from 0 to 13. Age and obesity were each significantly and independently associated with an increased risk of cholecystectomy. When adjusted for differences in age and obesity, those who had had five or more pregnancies had a significantly increased risk of cholecystectomy. We conclude that an increased risk of gallbladder disease may follow either obesity or multiple pregnancies. One possibly unifying hypothesis for the obesity and pregnancy association is sustained hyperestrogenemia.

A case-control study of gallstones: a major risk factor for biliary tract cancer

Because of the strong association between gallstones and biliary tract cancer, we conducted a case-control study of gallstones at Niigata Cancer Center Hospital. Eighty-six cases with gallstones (33 males and 53 females) and 116 hospital controls (56 males and 60 females) were surveyed by means of a self-administered questionnaire. Gallstones were categorized into cholesterol stones (25 cases) and pigment stones (30 cases) based on the appearance of the stones. In multivariate analyses based on an unconditional logistic regression model, the risk of total gallstones was positively associated with a taste for salty food (relative risk (RR) = 2.31, 95% confidence interval (CI): 1.10-4.84), an intake of lettuce and cabbage (RR = 2.98, 95% CI: 1.47-6.06) and a family history of biliary diseases (RR = 5.63, 95% CI: 1.76-17.95), and inversely associated with an intake of salted and dried fish (RR = 0.16, 95% CI: 0.04-0.64). When analyzed by type of stones, cholesterol stones were associated with a taste for oily food (RR = 3.87, 95% CI: 1.36-11.03) and pigment stones were positively associated with professional or administrative occupation (RR = 4.74, 95% CI: 1.35-16.68) and inversely associated with a taste for less greasy food (RR = 0.28, 95% CI: 0.10-0.83). Some of these results are consistent with the results of our previous study on biliary tract cancer.

Effect on pregnancy on gallstone formation

An ultrasound study was carried out to determine the incidence of gallstone formation during pregnancy. One hundred and thirty seven pregnant women attending antenatal clinics were studied; 70 women were primigravidas and 67 were 1 para or more. An ultrasound of the gallbladder was carried out at 20 weeks or less of gestation and a repeat of ultrasound examination was performed soon after delivery. Five women had gallstones diagnosed before pregnancy; 1 of these was a primigravida, the other 4 were para 1 or more. None of the women developed gallstones during pregnancy. This finding suggests that pregnancy is unlikely to be an important factor in gallstone formation.

Weight, diet, and the risk of symptomatic gallstones in middle-aged women

To assess the risk factors for symptomatic gallstones, 88,837 women in the Nurses' Health Study cohort (age range, 34 to 59 years) were followed for four years after completing a detailed questionnaire about food and alcohol intake in 1980. A total of 433 cholecystectomies and 179 cases of newly symptomatic, unremoved gallstones, diagnosed by ultrasonographic examination or x-ray films, were reported during the four-year follow-up. The age-adjusted relative risk for very obese women, who had a Quetelet index of relative weight (weight in kilograms divided by the square of the height in meters) of more than 32 kg per square meter, was 6.0 (95 percent confidence interval, 4.0 to 9.0), as compared with women whose relative weight was less than 20 kg per square meter. For slightly overweight women (relative weight, 24 to 24.9 kg per square meter), the relative risk was 1.7 (95 percent confidence interval, 1.1 to 2.7). Overall, we observed a roughly linear relation between relative weight and the risk of gallstones. Among the 59,306 women whose relative weight was less than 25 kg per square meter, a high energy intake (greater than 8200 J per day), as compared with a low energy intake (less than 4730 J per day), was associated with an increased incidence of symptomatic gallstones (relative risk, 2.1; 95 percent confidence interval, 1.4 to 3.3), and an alcohol intake of at least 5 g per day was associated with a decreased incidence as compared with abstention (relative risk, 0.6; 95 percent confidence interval, 0.4 to 0.8). Parity did not appear to be an important risk factor after an adjustment was made for relative weight. These data support a strong association between obesity and symptomatic gallstones and suggest that even moderate overweight may increase the risk.

Ethnic variation in cholecystectomy rates and outcomes, Manitoba, Canada, 1972-84

We used population-based data from the Province of Manitoba's universal health insurance plan to compare the cholecystectomy experience of Native Americans and non-Natives from 1972 to 1984. The age-adjusted cholecystectomy rates for Native females were higher than for non-Native females with the peak rate occurring at age 30-39 for Native Americans and at age 60-69 for non-Natives. The rates for males were three times lower than for females and did not differ between Natives and non-Natives. Native Americans were more likely readmitted to hospital for surgical complications than non-Natives and this held true after controlling for age, sex, rural versus urban residence, teaching versus non-teaching hospital, multiple discharge diagnoses or complex versus simple cholecystectomy (relative odds 1.46, 95 per cent confidence interval 1.17, 1.18). The explanation for the relatively high rates of cholecystectomy among Native American females may be related to high rates of known risk factors for gallstone disease (such as obesity and high parity). However, the higher rates of surgical complications require further study.

The epidemiology of gallstone disease in Rome, Italy. Part II. Factors associated with the disease. The Rome Group for Epidemiology and Prevention of Cholelithiasis (GREPCO)

The epidemiological associations of gallstone disease were evaluated in a population of 2,325 civil servants (1,244 men and 1,081 women) in Rome, Italy, which was enrolled in a cross-sectional survey on cholelithiasis. Participants were screened for the presence of gallstones by gallbladder ultrasonography, completed a questionnaire on family and personal history and underwent a physical examination and blood chemistry. Statistically significant associations were established by univariate analysis of the age-standardized data and by step-wise multiple logistic regression. At univariate analysis, increasing age, serum triglycerides and number of cigarettes smoked per day, and decreasing high-density lipoprotein-cholesterol were the conditions associated with the presence of gallstones in men. Age and parity were the correspondent associations in women. After controlling by multiple logistic regression, a different pattern of associated conditions emerged. In men, only age and serum triglycerides showed a significant positive association with gallstones, which was independent of other variables. In women, the presence of gallstones was independently associated with increasing age, number of pregnancies, body mass index and serum triglycerides, and with decreasing total (and low-density lipoprotein) cholesterol. The latter association was curvilinear in shape. The conditions associated with a history of cholecystectomy differed from those observed in subjects with gallstones, with the exceptions of age, in both sexes, and high serum triglycerides, in women. Fasting blood glucose levels were higher in women with a history of cholecystectomy than in those with or without gallstones, both at univariate and multiple logistic regression analyses.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-contraceptive estrogen use and the risk of gallstone disease in women

We interviewed 102 women, ages 41-74 years who underwent gallstone surgery between January 1979 and September 1980, and 98 controls selected from the membership files of a large prepaid health care plan in Western Washington, about their past use of certain medications, reproductive history, and physical and demographic characteristics. The risk of gallstone disease among women who used estrogens for at least one year prior to diagnosis of their condition, relative to that of other women, was 1.18 (95% CI: 0.65-2.13). Standardization for the effects of age, race, obesity, parity, thiazide use, and history of high blood pressure did not alter appreciably the estimate of relative risk. Among estrogen users, the duration of use was similar in cases and controls. Our findings suggest that if non-contraceptive estrogen use is a risk factor for gallstone disease (requiring surgery) in women, its effect is very small.

Gall stones in a Danish population: fertility period, pregnancies, and exogenous female sex hormones

From a cross sectional study of gall stone disease ascertained by ultrasonography, the prevalence in relation to age at menarche, use of oral contraceptives, childbirths, breastfeeding, abortions, age at menopause, and menopausal hormone therapy was assessed. The random sample comprised 2301 women of Danish origin aged 30, 40, 50, and 60 years, of whom 1765 (77%) attended the investigation. Gall stone disease was significantly associated with young age at menarche, abortions, and multiple childbirth. Use of oral contraceptives was significantly associated with gall stone disease in univariate analysis, but not in multivariate analysis. Breastfeeding, age at menopause and menopausal hormone therapy were not associated with gall stones. These determining variables seemed sufficient to explain the higher prevalence of gall stone disease in women than in men.

Origin and fate of biliary sludge

Biliary sludge is a collection of mucus, calcium bilirubinate, and cholesterol crystals that is usually recognized by characteristic echoes on ultrasonography. Its pathogenesis, clinical significance, and ultimate prognosis remain uncertain. We therefore studied the origin of biliary sludge ultrasonic echoes, using an ex vivo liver-gallbladder preparation, and determined the outcome of a group of patients identified to have gallbladder sludge by ultrasonography. Echoes were not generated by either an increase in the total solid concentration or by the graded addition of partially purified mucus glycoprotein. Cholesterol monohydrate crystals (greater than 50 micron) mixed with mucus produced echoes that were indistinguishable from gallbladder sludge observed in patients. To determine the natural evolution of gallbladder sludge in patients, we prospectively followed 96 patients found to have biliary sludge for a mean of 37.8 mo by serial ultrasound scans every 6 mo. In 17 patients (17.7%) biliary sludge disappeared and did not recur for at least 2 yr, in 58 patients (60.4%) biliary sludge disappeared and reappeared, and in 8 patients (8.3%) asymptomatic gallstones developed. There were 12 cholecystectomies performed: six were done for symptomatic gallstones (6.3%) and the other six for sludge associated with severe biliary pain attacks with or without recurrent acute pancreatitis. The finding of sludge represented precipitates being formed in bile. In some patients, it was a precursor form of gallstone disease.

Direct measurements of enterohepatic circulation of bile acids in the cat. Influence of contraceptive steroids and oophorectomy

Contraceptive steroids that increase the risk of gallstones reduce the bile acid pool size and increase the cholesterol saturation in bile. To analyze mechanisms behind these effects, bile acid enterohepatic circulation was studied with direct methods in cats treated with peroral contraceptive steroids for 3 months, cats oophorectomized 1-2 months before study, and female control animals. Both administration of contraceptive steroids and oophorectomy reduced the bile acid pool size and bile acid synthesis rate. Contraceptive steroids increased water secretion by the liver at low bile acid secretion rates, reduced bile acid accumulation in the gallbladder, and increased the recycling rate of the bile acid pool. Oophorectomy did not significantly change the relation between bile acid and water secretion by the liver. The reduced bile acid pool size in animals receiving contraceptive steroids can be explained by an increased recycling rate induced by an enhanced water secretion by the liver. The possibility of a direct effect on the hepatic synthesis of bile acids by both administration of contraceptive steroids and oophorectomy cannot be excluded.

Long term effects of childbearing on health

Information on whether a woman had ever had any children was recorded for all deaths registered to ever-married women in England and Wales between 1938 and 1960. Analysis of the relation between parity and cause of death for 1.2 million women aged 45-74 years revealed that parous women had lower mortality from breast, ovarian, and endometrial cancer than did nulliparous women but a higher mortality from diabetes mellitus, gallbladder disease, cancer of the uterine cervix, nephritis and nephrosis, hypertension, ischaemic and degenerative heart disease, cerebrovascular disease, and all causes of death. There is a parallel between the long term effects of pregnancy and of oral contraceptives on health.

Plasma lipids and insulin in gall stone disease: a case-control study

Fasting plasma lipid and insulin concentrations were measured in 173 patients with gall stones and 284 hospital controls to investigate their relationship to this disease. Multivariate methods of analysis were used to estimate the net associations between individual plasma variables and the risk of developing gall stones. In both sexes increased plasma insulin values were associated with an increased risk of gall stones independently of plasma triglyceride values; increased plasma triglyceride concentrations were associated with an increased risk of gall stones in young subjects only; increased plasma total cholesterol concentrations were associated with a decreased risk of gall stones only after controlling for plasma insulin and triglyceride concentrations; while increased plasma high density lipoprotein cholesterol concentrations were associated with a decreased risk of gall stones, but were confounded by plasma insulin and triglyceride values. These associations were independent of obesity and dietary intake.