In a quasi-simultaneous assessment, imprecise cholesterol monitoring and screening tests were improved

OBJECTIVE: To calibrate Reflotron-measured capillary total cholesterol (cTC) relative to a laboratory-measured venous total cholesterol (vTC) criterion standard for monitoring and screening hypercholesterolemia. STUDY DESIGN AND SETTING: Quasi-simultaneous assessment in 1999-2002 of Reflotron cTC and laboratory vTC in a random sample of 4,269 adult residents of Geneva, Switzerland (calibration development subsample n=3,067; validation subsample n=1,172), by means of bias, precision, correlation, sensitivity, and false positive percentage (calculated as 100-specificity) analyses of Reflotron cTC vs. laboratory vTC measures for predicting hypercholesterolemia. RESULTS: Total bias was small (-0.26 mmol/L), but there was substantial negative drift in Reflotron cTC (annual biases +0.08, -0.17, -0.27, and -0.60 mmol/L in 1999-2002). Overall, 57% of Reflotron cTC measurements for 894 hypercholesterolemic patients underestimated laboratory vTC (2%, 57%, 71%, and 98% in 1999-2002). Prior to calibration, sensitivity was 73% for the development and 35% for the validation subsample, with false positive at 4% (development) and 0.1% (validation). After calibration, sensitivity was 78% for the development and 37% for the validation subsample, with false positive at 5% (development) and 0.2% (validation). Using 95% upper prediction limits (UPL) for individual vTC values increased sensitivity to 99% and 83% and false positive percentage to 30% and 7% for the development and validation subsamples, respectively. CONCLUSION: Crude results of Reflotron-measured cTC have poor sensitivity. Instead, 95% UPL can be used for monitoring and screening. Simply adding 0.8 mmol/L to a patient's observed Reflotron cTC value provides a very good approximation to the 95% UPL.     

Audit of near patient cholesterol testing in occupational health clinics

An audit of near patient cholesterol testing was carried outin occupational health clinics. The aims were to examine thestatistical agreement between Reflotron and laboratory measurementsof blood cholesterol and to formulate a policy for the use ofReflotrons in cholesterol testing. Three hundred and fifty-twostaff members attending occupational health clinics over a periodof 10 months had blood taken for both Reflotron and laboratorymeasurements. The correlation between the two methods was 0.95.The Reflotron had a negative bias compared to the laboratory,with the mean difference between the two methods of measurementbeing –0.21 mmol/l (95 per cent confidence interval –0.18to –0.25mmol/l). Despite the high correlation coefficientand small mean difference, the scatter of Reflotron-laboratorydifferences was broad, with 95 per cent of the differences lyingin the range of 0.95 mmol/l below to 0.52 mmol/l above the laboratoryresult. For Reflotron results of 5.50 mmol/l and greater, thesensitivity and specificity of the Reflotron in detecting subjectswith laboratory cholesterol levels greater than 6.5 mmol/l were100 per cent and 70 per cent respectively. The laboratory participatedin two external quality assessment schemes for cholesterol testingduring the course of the audit and all the results of thesefell within the acceptable limits. The audit demonstrated thatthe Reflotron was too imprecise to be used to give accuratemeasurements of blood cholesterol. However, providing a suitableReflotron result above which patients were sent for confirmatorylaboratory testing was selected, it was an acceptable screeningdevice in the detection of hypercholesterolaemia. Other Reflotronusers should consider carrying out similar audits.     

Performance characteristics of a blood cholesterol measuring instrument used in screening programs

Four experiments were conducted to assess the precision and accuracy of the Boehringer Mannheim Diagnostics Reflotron, an instrument that is being adopted by many public health groups to conduct blood cholesterol screening programs. Our study is one of the first to evaluate and document the instrument's performance characteristics. Successive generations of reagent tabs supplied by the manufacturer were tested against a reference laboratory method standardized by the Centers for Disease Control. Three of the experiments also compared two or more Reflotrons to assess intermachine reliability. The Reflotron analyzer provided precise blood cholesterol measurements both in repeated tests and among instruments. The accuracy of the method varied across reagent lots, with an average negative bias of 21.05 milligrams per deciliter (mg per dl), decreasing steadily to a negative bias of 4.07 mg per dl. Reliability between and within analyzers was high. The data provide support for the use of the instrument in blood cholesterol screening efforts, yet signal the need for attention to quality control procedures, both by the manufacturer and operators, to ensure the validity and accuracy of the results.     

Plasma lipids and their interrelationship in Turkish adults.

STUDY OBJECTIVE--The aim was to describe the plasma total cholesterol and triglyceride profiles in a random sample of Turkish adults and analyse the effects of certain coronary risk factors on these levels. DESIGN--This was a cross sectional population based survey. SETTING--59 communities scattered in all seven geographical regions of Turkey were surveyed in the summer of 1990. SUBJECTS--A random sample of 3689 men and women 20 years of age and over was studied. MEASUREMENTS AND MAIN RESULTS--Plasma total cholesterol, triglycerides, glucose (using Reflotron and with partial validation in reference laboratory), weight, height, and blood pressure were measured, and information on smoking, physical activity, and family income obtained. Hypercholesterolaemia (> or = 6.5 mmol/litre, 250 mg/dl) prevailed in 8.5%, and hypertriglyceridaemia (> 2.25 mmol/litre, 200 mg/dl) in 16.6% among men and women aged 40-59 years of age. Age adjusted total cholesterol values were 4.8 mmol/litre (185 mg/dl) in men and 5 mmol/litre (192 mg/dl) in women. A steep rise appeared in mean cholesterol levels between the ages of 20-29 and 40-49 years, in a ratio greater than the available data from some other populations indicated. Mean total cholesterol values increased substantially in both genders with diminishing grades of physical activity, rising serum triglyceride levels, in urban (opposed to rural) residents, in men with increasing income levels, and in the younger adults with rising body mass index. CONCLUSIONS--Turkish adults have comparatively low levels of total cholesterol and medium to moderately high levels of triglycerides. Lifestyle factors affect these levels in Turks as in other populations.     

Precision of a dry-chemistry method of lipid screening

OBJECTIVES: The purpose of this study was to compare total capillary cholesterol values acquired using the Reflotron with a venous sample taken simultaneously, to determine if the Reflotron meets the guidelines of the National Cholesterol Education Program (NCEP) for accuracy. STUDY DESIGN: An announcement and a registration form for a cholesterol screening programme were distributed with employee pay slips at a large southern university. Approximately 15 employees were scheduled for each screening date, with walk-ins allowed at the health assessment site as space allowed. Capillary and venous samples were collected from screening participants (n=285). METHODS: Approximately 20 ml of blood was collected from each participant, after fasting for 12 h, using standardized venepuncture techniques in the antecubital vein in the bend of the elbow. In order to overcome technician error, two drops of blood (30 microl) were collected immediately from the previously drawn venous sample by drawing blood into the capillary tube from the opening in the top of the venous tube before centrifuging the venous sample, rather than 'sticking' the finger. RESULTS: A Kolmogorov-Smirnov (KS) test of normality was calculated for total capillary cholesterol (KS=1.27, P=0.79) and total venous cholesterol (KS=0.99, P=0.28), which revealed insufficient evidence that the distributions were not normal. Participants' total capillary cholesterol values averaged 213.27 mg/dl [standard deviation (SD)=44.66 mg/dl)] when analysed on the Reflotron, and slightly higher (228.86 mg/dl, SD=40.50 mg/dl) for venepuncture. A paired t-test for variance between groups revealed significant differences in total capillary and total venous cholesterol values (t=-41.93, P<0.0001). A mean centered coefficient of variation was performed, revealing a 3.3% error rate, i.e. greater than the 3% allowable by the NCEP III guidelines. The mean percent bias was -7.28% (SD=3.10%) and the absolute mean percent bias was 7.46% (SD=2.64%). The percentage of participants with total cholesterol misclassified was 16.85%. Concomitantly, Spearman correlation coefficients were high (r2=0.94, P=0.01). CONCLUSIONS: Although the Reflotron met most of the NCEP III guidelines for accuracy, the portable analyser provided clinically relevant underestimations of total cholesterol values, especially for the lower and upper values. Consequently, lipid values obtained using the Reflotron may be useful for screening, but the Reflotron should not be used as a diagnostic and management tool.     

Existence of consistent hypo- and hyperresponders to dietary cholesterol in man

Hyper- and hyporesponsiveness of serum cholesterol to dietary cholesterol is an established concept in animals but not in man. The authors studied the stability of the individual response of serum cholesterol to dietary cholesterol in three controlled experiments in 1982. The subjects were volunteers from the general population living in or near Wageningen, the Netherlands. Each experiment had a low-cholesterol baseline period (121, 106, and 129 mg/day in experiments 1, 2, and 3, respectively) and a high-cholesterol test period (625, 673, and 989 mg/day). Duplicate portion analysis showed that dietary cholesterol was the only variable. The 94 healthy men and women who completed experiment 1 showed an increase (mean +/- standard deviation (SD] in serum cholesterol of 0.50 +/- 0.39 mmol/liter (19 +/- 15 mg/dl). Seventeen putative hyperresponders, defined by their response in experiment 1, were retested in experiments 2 and 3; they showed responses of 0.28 +/- 0.38 mmol/liter (11 +/- 15 mg/dl) and 0.82 +/- 0.35 mmol/liter (32 +/- 14 mg/dl), respectively. Fifteen hyporesponders, selected in experiment 1, showed responses in experiments 2 and 3 of 0.06 +/- 0.35 mmol/liter (2 +/- 14 mg/dl) and 0.47 +/- 0.26 mmol/liter (18 +/- 10 mg/dl), significantly lower than the corresponding values for hyperresponders. The standardized regression coefficient for individual responses in experiment 2 on those in experiment 1 was beta = 0.34 (p = 0.03, n = 32); the corresponding regression coefficient for experiment 3 and experiment 1 was 0.53 (p less than 0.01). After correction for intraindividual fluctuations the true responsiveness distribution was found to have a between-subject standard deviation of about 0.29 mmol/liter (11 mg/dl). This implies that if the mean response to a certain dietary cholesterol load amounts to e.g., 0.58 mmol/liter (22 mg/dl), then the 16% of subjects least susceptible to diet will experience a rise of only 0.29 mmol/liter (11 mg/dl) or less, while in the 16% of subjects most susceptible to diet, serum cholesterol will rise by 0.87 mmol/liter (34 mg/dl) or more. The authors conclude that modest differences in responsiveness of serum cholesterol to dietary cholesterol do exist in man, and that the wide scatter of responses observed in single experiments is largely due to chance fluctuations.     

An evaluation of the Reflotron(R) for the determination of plasma cholesterol in capillary blood. Effect of operator variability

The availability of portable analysers potentially puts thedetection of individuals with high serum cholesterol levelson a similar footing to that of high blood pressure. The Reflotron^®,which can make cholesterol measurements on capillary blood sampleswithout the need for centrifugation, has been evaluated in clinicalpractice. In 94 consecutive patients capillary blood was usedfor the determination of serum cholesterol by the Reflotron,by a laboratory technician (n=37) and by a nursing sister (n=57).Venous blood was also taken from the same patients within afew minutes of the capillary sample for enzymic determinationof serum cholesterol at the hospital laboratory. Overall, theReflotron values were about 0.6 mmol/l lower than those obtainedat the hospital laboratory. The accuracy and precision of theresults obtained by the nurse were poorer than those obtainedby the technician, even though the nurse had attended a threeday training course. Our results indicate that the Reflotronis a suitable instrument for use in screening for serum cholesterol,provided personnel operating the machine have adequate trainingand experience, and provided it is borne in mind that the resultsobtained may be slightly lower than standard laboratory methods.     

Trend in serum total cholesterol level in 110,000 young adults in The Netherlands, 1974 to 1986.

Data from two screening projects on cardiovascular risk factors were used to analyze the trend in serum total cholesterol level in the Netherlands between 1974 and 1986. Cholesterol levels were measured in a single reference laboratory of the World Health Organization throughout the entire study period. Between 1974 and 1980, about 30,000 men and women aged 37 to 43 years (mean age, approximately 40 years) were screened. A decrease in mean serum total cholesterol level was observed until the end of 1977, when it was followed by an increase. This resulted in a net change over the entire study period of -0.07 mmol/liter (3 mg/dl) in men and -0.03 mmol/liter (1 mg/dl) in women. Between 1981 and 1986, about 80,000 men aged 33 to 37 years (mean age, 35 years) were screened. During this period, a decrease of 0.20 mmol/liter (8 mg/dl) in the mean total cholesterol level was observed. In spite of the decline in the mean total cholesterol level, the prevalence of cholesterol values of greater than or equal to 6.5 mmol/liter (greater than or equal to 251 mg/dl) in young adult men was still high in 1986 (16 percent). A further reduction is therefore desirable. The decline in the mean total cholesterol level in young adults might indicate that a further decline in mortality from coronary heart disease can be expected.     

Interpreting tests for iron deficiency among adults in a high HIV prevalence African setting: routine tests may lead to misdiagnosis

We evaluated peripheral blood tests to diagnose iron deficiency on medical wards in Blantyre, Malawi, where infection and HIV are prevalent. We compared full blood count, ferritin and serum transferrin receptor (TfR) levels with an estimation of iron in bone marrow aspirates. Of consecutive adults admitted with severe anaemia (haemoglobin <7 g/dl), 81 had satisfactory bone marrow aspirates. The main outcome measures were the validity of each test (sensitivity, specificity, and positive and negative predictive values) and likelihood ratios (LR) for iron deficiency. Twenty patients (25%) were iron deficient and 64 (79%) were HIV-positive. Iron deficiency was more common in HIV-negative compared with HIV-positive patients (59% vs. 16%; P<0.001). In HIV-positive patients, the optimal ferritin cut-off was 150 microg/l (sensitivity 20%, specificity 93%, LR 2.7), but no test was accurate enough to be clinically useful. In HIV-negative patients, ferritin was the single most accurate test (cut-off <70 microg/l, 100% specificity, 90% sensitive, LR if positive infinity, LR if negative 10). TfR measurement did not improve the accuracy. Mean cell volume was not a good predictor of iron status except in HIV-negative patients (cut-off <85 fl, specificity 71%, sensitivity 90%). In populations with high levels of infection and HIV, an HIV test is necessary to interpret any tests of iron deficiency. In HIV-negative patients, ferritin is the best blood test for iron deficiency, using a higher cut-off than usual. For HIV-positive patients, it is difficult to diagnose iron deficiency without bone marrow aspirates.     

Reflotron performance in a community screening program: results of the Massachusetts Model Systems for Blood Cholesterol Screening Project.

We evaluated the precision, accuracy, and durability of the Reflotron portable analyzer as part of the National Heart, Lung, and Blood Institute's Model Systems for Blood Cholesterol Screening Program. We conducted screenings in a wide variety of settings in four Massachusetts communities over a 16-month period. Fingerstick samples from 10,428 individuals were tested on the Reflotron at the screening sites. For comparison, we drew venous samples from 972 participants and analyzed them in a reference laboratory, which had met the requirements of the Centers for Disease Control's Lipid Standardization Program. All four Reflotrons tested met the 1988 guidelines for precision and accuracy established by the Laboratory Standardization Panel (LSP) of the National Cholesterol Education Program (NCEP). None of the analyzers consistently met the 1992 LSP standards for precision, although two met the 1992 standards for accuracy. More than 40% of Reflotron values differed from the reference laboratory values by more than 5%. As a consequence, more than 16% of individuals were misclassified in terms of the NCEP risk category into which their Reflotron readings fell. All four instruments malfunctioned at some point during the project, precluding their further usage. We recommend improvements in the precision, accuracy, and durability of this analyzer.     

上海市35-74岁成人代谢综合征腰围切点的研究

［目的］ 探寻上海市35-74 岁人群中代谢综合征（metabolic syndrome,MS）相关肥胖程度的腰围切点。 ［方法］采用多阶段随机抽样方法,在上海市35~74 岁居民中进行横断面调查,共调查7 414 名个体。分析男性和女性不同腰围水平与MS 其他因素的关系,以获得检出2 个及以上危险因素敏感性和特异性均较好的腰围切点。 ［结果］ 随腰围增大,MS 危险因素聚集的比值比（OR）也随之升高,检出2 个及以上MS 危险因素的特异度和阳性预测值逐渐增高,而敏感度和阴性预测值逐渐下降。当男性腰围≥ 85 cm、女性腰围≥ 80 cm,检出2 个及以上MS 危险因素的敏感度为68.33%（男性）、70.17%（女性）,特异度为58.48%（男性）、58.36%（女性）,受试者工作特征曲线（ROC）距离最短,分别为男性0.522 1、女性0.512 2。 ［结论］ 当男性腰围≥ 85 cm、女性腰围≥ 80 cm时,能较好反映MS 危险因素的聚集,为本研究人群代谢综合征肥胖的腰围切点。     

Self-report of high cholesterol: determinants of validity in U.S. adults

BACKGROUND: Hypercholesterolemia is a major cardiovascular risk factor, and cholesterol awareness is important in both clinical practice and in public health. We evaluated the validity of self-reported hypercholesterolemia and identified determinants of validity. METHODS: The study design was a cross-sectional survey, from 1988 to 1994, of adult participants (N=8236) from the Third National Health and Nutrition Examination Survey for whom self-report of hypercholesterolemia and serum measurement were available. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for self-reported hypercholesterolemia were calculated using total cholesterol > or =5.17 mmol/L (200 mg/dL) and/or taking cholesterol-lowering medication as the criterion standard. RESULTS: Overall test characteristics for self-report were sensitivity, 51%; specificity, 89%; PPV, 87%; and NPV, 55%. Sensitivity of self-report was higher among older subjects and non-Hispanic whites, specificity was higher among subjects with >12 years of education, PPV was higher in older subjects, and NPV was higher in younger subjects and in those with >12 years of education. Using higher cholesterol thresholds to define hypercholesterolemia led to higher sensitivity, lower specificity, lower PPV, and higher NPV. Sociodemographic and anthropometric predictors of validity were identified by logistic regression. CONCLUSIONS: Due to low sensitivity, self-reported hypercholesterolemia should be used with caution, both during the patient encounter and for surveillance of trends in hypercholesterolemia in the absence of measured cholesterol levels. Specificity is consistently much higher than sensitivity. The high PPV may be of use in certain clinical situations. Such validation studies should form the foundation for future research based on self-report.     

Belgian heart disease prevention project: comparison of self-reported smoking behaviour with serum thiocyanate concentrations.

At the end of a multifactorial cardiovascular preventive trial serum thiocyanate was measured in random samples of 1035 cases and 1087 controls. A cut-off point 0.45 mg/dl (77.6/mumol/l) gave a sensitivity of 82.1% among the cigarette smokers in the control group and a specificity of 91.0% among the non-smokers. When the intervention and control groups are compared in terms of self-reported smoking behaviour non-significant differences in mean thiocyanate concentration are observed for those who never smoked, ex-cigarette smokers, actual cigarette smokers, and in four different cigarette smoking categories. Our results fail to confirm the reported pessimistic views concerning the validity of self-reported smoking behaviour in subjects taking part in intervention trials.     

北京社区体检人群餐后与空腹血脂水平的比较分析及意义

目的:探讨非空腹血脂异常判定标准在北京社区人群中应用的可行性。方法:采用自身对照研究。中国中医科学院广安门医院检验科于2018年1至10月招募社区体检者839名（男性292名,女性547名）,年龄中位数（四分位间距）为60（54, 66）岁,同时检测空腹和标准餐后4 h血脂谱水平,采用配对 t检验或者配对非...     

Performance of the Reflotron in Massachusetts' Model System for Blood Cholesterol Screening Program.

The precision, accuracy, and durability of the Reflotron were evaluated by the Massachusetts Model Systems for Blood Cholesterol Screening Program. Screenings were conducted in diverse community settings over 16 months. Fingerstick samples from 10,428 individuals were tested. None of the four analyzers met the 1992 standards for precision, although two met the 1992 standards for accuracy. More than 40% of Reflotron values differed from the reference laboratory values by upwards of 5%. More than 16% of individuals were misclassified in terms of their risk category. All four instruments malfunctioned during the project.     

Accuracy and precision of HDL cholesterol measurements using an office chemistry analyzer

BACKGROUND. A physician can obtain a patient's complete lipoprotein profile at the time of the office visit including assays of the total serum cholesterol, high-density lipoprotein cholesterol (HDL-C), and fasting triglyceride concentrations, and then calculate the low-density lipoprotein cholesterol (LDL-C). Until recently, this was not possible. Instruments are currently available that provide reliable rapid total serum cholesterol and fasting triglyceride measurements. METHODS. This study evaluated the accuracy and precision of a recently developed analytical method for the rapid measurement of HDL-C (Seralyzer Cholesterol System) as compared with a reference clinical laboratory method (Kodak Ektachem 700 XR). Blood specimens were taken from 90 participants and were analyzed in duplicate for HDL-C concentrations and total cholesterol using the Seralyzer and a standard Ektachem 700 XR. RESULTS. Nearly all (98.9%) of the initial Seralyzer HDL-C measures were within +/- 0.08 mmol/L (+/- 3 mg/dL) of the duplicate Seralyzer values. Most (98.3%) of the Seralyzer HDL-C results were within +/- 0.16 mmol/L (+/- 6 mg/dL) of the Kodak HDL-C values. CONCLUSIONS. The Seralyzer HDL-C test provides a reliable and accurate measure of the HDL-C concentration.     

指尖毛细血管空腹血糖筛查糖尿病和糖尿病前期的切点及应用

目的 探讨指尖毛细血管空腹血糖(指尖FPG)筛检社区45岁以上人群糖尿病和糖尿病前期[空腹血糖受损(IFG)、糖耐量低减(IGT)]的切点,为人群普查提供依据.方法 随机整群抽取保定市3个社区,以社区内45岁以上居民3250人为筛查对象.对指尖FPG≥5.1 mmol/L者进行75 g口服葡萄糖耐量试验(OGTT),测空腹血糖及服糖2 h静脉血浆血糖(2hPG),诊断糖尿病和糖尿病前期.应用受试者工作(ROC)曲线确定糖尿病及IFG、IGT的切点,判断诊断价值.结果 检出糖尿病230例(7.3%),IFG 166例(5.2%),IGT 204例(6.7%);以指尖FPG为测试变量,以是否FPG≥7.0 mmol/L及或2hPG≥11.1 mmol/L为说明变量ROC曲线分析,曲线下面积为0.905,最佳切点为6.0 mmol/L,最大灵敏度和特异度分别是78.0%和89.3%;以是否FPG<5.6 mmol/L、是否FPG<7.0 mmol/L及7.8 mmol/L≤2hPG≤11.1 mmol/L为说明变量ROC曲线分析,曲线下面积分别为0.633、0.719,最佳切点均为5.7 mmol/L,灵敏度和特异度均较低(50.3%、28.0%;60.8%、28.0%).结论 用指尖FPG 6.0mmol/L为切点筛查45岁以上人群糖尿病,相对可靠;但指尖FPG筛查IFG、IGT不可靠.指尖FPG筛查社区人群简便、快捷,有一定的应用意义.     

Measuring blood cholesterol outside the pathology laboratory: issues of accuracy and reliability.

Desk-top analysers that are simple to use, portable and free from technical requirements are now widely used for blood cholesterol measurement outside the traditional pathology laboratory setting. Test accuracy and reliability are essential if these portable desk-top analysers are to be of value in the assessment and management of elevated blood cholesterol. To determine their accuracy and reliability we compared the results obtained from four different desk-top analysers with those from a teaching hospital's routine laboratory method. The desk-top analysers assessed were the Ames Minilab, the Kodak DT60, the Boehringer Reflotron and the Abbott Vision. The precision of each desk-top analyser was within acceptable limits, defined as a coefficient of variation less than 5 per cent. The results from the Vision, Reflotron and DT60 related closely to those from routine laboratory method, with least squares linear regression slopes ranging from 0.92 to 1.06 and intra-class correlation coefficients from 0.95 to 0.99. The Minilab showed least agreement with the routine laboratory method and caution should be taken in the interpretation of cholesterol estimations made with this device.     

Validity of hospital discharge International Classification of Diseases (ICD) codes for identifying patients with hyponatremia

Medical diagnosis can be studied using various sources of information, such as medical and hospital discharge records and laboratory measurements. These sources do not always concur. The objective of the present study was to assess the sensitivity, specificity, and positive and negative predictive values of hospital discharge diagnosis compared with clinical laboratory data for the identification of hyponatremia. Patients with hyponatremia were selected from a hospital information system determined by the International Classification of Diseases, 9th edition (ICD-9). The validity parameters for hyponatremia (ICD code 276.1) were estimated by comparison with accurate serum sodium (Na+) levels. A total of 2632 cases of hyponatremia were identified using laboratory measurements (Na+ < or =135 mmol/L). The sensitivity of ICD coding for hyponatremia was maximally about 30% for patients with very severe hyponatremia (Na+ < or =115 mmol/L). Corresponding specificities were high (>99%). In 87% of the cases with severe hyponatremia (Na+ < or =125 mmol/L), other discharge ICD codes reflecting severe morbidity were found. This study suggests that ICD codes for hyponatremia represent only one third of the patients admitted to the hospital and experiencing hyponatremia. About two thirds of the patients with hyponatremia were classified as hospitalized for other reasons. To assess the validity of case finding of patients with hyponatremia, the use of analytical techniques, such as certain laboratory measurements, is advisable.     

A simple index for detection of gestational diabetes mellitus

The conventional screening test for gestational diabetes mellitus is measurement of plasma glucose 1 hour after 50 g glucose by mouth. The sensitivity and specificity of this test are lower than desirable; we therefore developed an index including other plasma constituents. In a preliminary study, 138 pregnant women had the standard oral glucose load screening test, and plasma fructosamine and total proteins were measured, in addition to glucose, in the 1-hour samples. An index value (I) was calculated as [fructosamine (micro mol/L) divided by total proteins (g/L)]x[glucose (mmol/L) divided by 100]. Cut-off values for I were then assessed in a second prospective study, of 642 pregnant women. Definitive diagnosis of gestational diabetes was by oral glucose tolerance test (OGTT). The index was also assessed in terms of fetal macrosomia (birthweight>or=4000 g). With a cut-off value of I=27.2, sensitivity was 98%, specificity 89%, diagnostic efficiency 90%, positive likelihood ratio 8.76. Application of the index would have avoided 42% of the OGTTs demanded by the standard screening test, reducing false positives from about 24% to 10%. Predictive efficacy for macrosomia was 10.3% versus 7.9%. Our index offers an efficient screening test for gestational diabetes, and with more stringent cut-off points may be applicable as a single-step diagnostic procedure.