Improving the utilization of clinical laboratory tests

Reimbursement policies for health care services are greatly diminishing in the U.S. and Western Europe. Hence, there is an increasing need for doctors and other care givers to reduce costs without compromising the quality of the care being delivered. The clinical laboratory is viewed as an area of high costs where significant reductions have been targeted. Efficient utilization of laboratory services can be achieved by elimination of the general health panel, removal of old tests or those that provide redundant information, a reduction in the use of standing orders, more judicious use of drug assays, acceptance of clinical practice guidelines, and use of reflex testing algorithms. New technologies such as DNA probes can substantially improve diagnostic efficiency. Point-of-care testing devices which have higher costs than incremental central laboratory expenses should only be used if they reduce overall operating expenses. Implementation of expert systems can make remaining tests more effective. Doctors and laboratorians must collaborate to achieve more efficient utilization practices.

Comparison of cardiac troponin I, creatine kinase-MB, and myoglobin for detection of acute ischemic myocardial injury in a swine model

To study the comparative value of the levels of cardiac troponin I (cTnI), creatine kinase-MB isoenzyme (CK-MB), and myoglobin in the detection of acute ischemic myocardial injury, we serially measured plasma concentrations of these cardiac proteins in 12 pigs with myocardial ischemia subtending severe coronary artery stenoses and in 5 pigs with a sham operation performed, but without coronary artery stenosis. In the stenosis group, flow in the left anterior descending (LAD) artery was reduced by 36% and maintained for 24 hours (n = 3), 7 days (n = 6), or 4 weeks (n = 3). Flow in the coronary artery was measured by a flowmeter, and regional left ventricular dysfunction was monitored by echocardiography. Myocardial infarction was identified with triphenyltetrazolium chloride staining. All pigs with stenosis of the LAD had significant ultrastructural abnormalities consisting of loss of myofibrils and an increase in mitochondria and glycogen deposition. Cardiac proteins were released in all pigs with stenosis of the LAD artery during the development of myocardial ischemia; the levels of cTnI, CK-MB, and myoglobin increased significantly relative to the baseline. The sensitivity and specificity for cTnI were higher than for CK-MB or myoglobin. Results of this study show that cTnI is the better marker for the detection of acute ischemic myocardial injury. Increased levels of cTnI can be found in reversible and irreversible myocardial ischemic injury in this model.

Prognostic role of troponin T versus troponin I in unstable angina pectoris for cardiac events with meta-analysis comparing published studies

Controversy exists as to the clinical roles and relative specificities of cardiac troponin T or I in patients with unstable angina pectoris (UAP). We measured troponin T and I levels on admission in 123 patients with UAP. Of the 107 patients with normal creatine kinase during the first 24 hours, troponin T and I were elevated in 14 and 13 patients, respectively. At 30 days, 5 of 14 patients (36%) with elevated troponin T and 3 of 93 patients (3.2%) with normal troponin T had acute myocardial infarction (odds ratio [OR], 16.7; 95% confidence interval [CI] 3.4 to 81.5; p <0.001). Of 13 patients with elevated troponin I, 5 patients (39%) and 3 of 94 patients (3.2%) with normal troponin I had acute myocardial infarction (odds ratio, 21.7; 95% CI 4.3 to 110; p <0.001). No deaths occurred within 30 days. Both markers demonstrated equivalent sensitivity (63%) and specificities (troponin T: 91%; troponin I: 92%) for myocardial infarction. Meta-analysis of 12 published troponin T and 9 troponin I studies in patients with UAP produced risk ratios of 4.2 (95% CI 2.7 to 6.4, p <0.001) for troponin I compared with 2.7 (95% CI 2.1 to 3.4, p <0.001) for troponin T. Comparison of the sensitivities and specificities of both markers using summary receiver operating characteristic curves showed no significant difference in their abilities to predict acute myocardial infarction and cardiac death. Troponin T and I show similar prognostic significance for acute myocardial infarction or death in the same patients with UAP. The 2 markers are equally sensitive and specific, as confirmed by meta-analysis, and this supports a role in risk stratification.

Integrity of Urine Specimens for Toxicological Analysis - Adulteration, Mechanisms of Action, and Laboratory Detection

Drug testing in urine for employees is an important deterrent for drug abuse. Because of the dire consequences of a positive result, many individuals who might otherwise test positive will go to great lengths to escape detection. The term "adulteration" in this context refers to: substitution of drug-free urine, purposeful ingestion of agents or fluids designed to either accelerate drug clearance or dilute urine such that drug concentrations are below administrative cutoffs (in vivo adulterants), and adding foreign substances after urine collection (in vitro adulterants) to interfere with drug assays (immunoassay screening and gas chromatography/mass spectrometry confirmation). For immunoassays, adulterants can interfere photometrically or alter antibody-antigen binding. For GC/MS analysis, in vitro adulterants can chemically alter the targeted drug to an undetectable derivative. The laboratory must use different schemes to detect adulterants, including physical observations and tests (e.g., color, odor, and pH), and chemical analyses (e.g., creatinine or glutaraldehyde). If the identity of the donated urine sample itself is in question, DNA tests can be performed. The laboratory must continue to develop new adulteration detection schemes as new adulterants are encountered.

Characterization of cardiac troponin subunit release into serum after acute myocardial infarction and comparison of assays for troponin T and I. American Association for Clinical Chemistry Subcommittee on cTnI Standardization

We examined the release of cardiac troponin T (cTnT) and I (cTnI) into the blood of patients after acute myocardial infarction (AMI). Three postAMI serum samples were applied in separate analytical runs onto a calibrated gel filtration column (Sephacryl S-200), and the proteins were separated by molecular weight. Using commercial cTnT and cTnI assays measured on collected fractions, we found that troponin was released into blood as a ternary complex of cTnT-I-C, a binary complex of cTnI-C, and free cTnT, with no free cTnI within the limits of the analytical methodologies. The serum samples were also examined after incubation with EDTA and heparin. EDTA broke up troponin complexes into individual subunits, whereas heparin had no effect on the assays tested. We added free cTnC subunits to 24 AMI serum samples and found no marked increase in the total cTnI concentrations, using an immunoassay that gave higher values for the cTnI-C complex than free cTnI. To characterize the cross-reactivity of cTnT and cTnI assays, purified troponin standards in nine different forms were prepared, added to serum and plasma pools, and tested in nine quantitative commercial and pre-market assays for cTnI and one approved assay for cTnT. All nine cTnI assays recognized each of the troponin I forms (complexed and free). In five of these assays, the relative responses for cTnI were nearly equimolar. For the remainder, the response was substantially greater for complexed cTnI than for free cTnI. Moreover, there was a substantial difference in the absolute concentration of results between cTnI assays. The commercial cTnT assay recognized binary and ternary complexes of troponin on a near equimolar basis. We conclude that all assays are useful for detection of cardiac injury. However, there are differences in absolute cTnI results due to a lack of mass standardization and heterogeneity in the cross-reactivities of antibodies to various troponin I forms.

Analytical and clinical evaluation of new diagnostic tests for myocardial damage

As with any new test, novel cardiac markers must meet basic analytical and clinical performance issues. For sensitivity and specificity, it is important to know what protein forms are released into blood after injury, and which of these forms are measured by the assays in question. When commercial tests become available, the choice of the measurement platform will be important in the timely delivery of results. The cut-off concentration used is also important, and requires careful selection of the patient groups to be studied. If the intent of the marker is to be used to diagnose acute myocardial infarction (AMI), data from normal subjects should not be included. However, low cut-off limits can be useful for detection of minor myocardial injury if the new assay is highly sensitive and specific. New tests are needed in the area of early diagnosis of AMI, detection of reinfarction or myocardial extension after AMI, risk stratification of patients with unstable angina, and therapeutic monitoring of patients with congestive heart failure. The most promising new markers are glycogen phosphorylase BB, free fatty acid binding protein, and brain natriuretic peptide.

Oral estrogen improves serum lipids, homocysteine and fibrinolysis in elderly men

The effects of estrogen on cardiovascular risk factors have been less well defined in men than in women. We measured lipid and lipoprotein concentrations, lipoprotein particle size distributions, lipoprotein (a), homocysteine, and markers of thrombosis and fibrinolysis in 18 [corrected] healthy elderly men (age 74 +/- 3 years, mean +/- S.D.) before and after 9 weeks of treatment with 0.5, 1 or 2 mg/day of oral micronized 17beta-estradiol. LDL-C (-6%), apo B (-9%), triglyceride (-5%), and homocysteine (-11%) concentrations decreased with estradiol, whereas HDL-C (+14%) increased. Intermediate-size VLDL subclass concentrations were lowered and LDL and HDL subclass levels altered in such a way as to cause average LDL and HDL particle size to increase. Lipoprotein (a) did not change. Fibrinogen (-13%) and plasminogen activator inhibitor-1 (PAI-1) concentrations (-26%) decreased, but there were no changes in thrombotic markers including thrombin-antithrombin III complex, prothrombin fragment 1.2, D-dimer, antithrombin activity, protein-C and S and von Willebrand factor antigen. Breast tenderness occurred in four men and heartburn in five but did not require discontinuation of treatment. We conclude that oral estrogen in men reduces homocysteine, fibrinogen, and PAI-1 concentrations and favorably influences VLDL, LDL and HDL subclass levels without increasing markers of thrombotic risk.

Multicenter evaluation of the Bayer Immuno I CA 15-3 assay

We conducted a multicenter evaluation of the analytical and clinical features of the automated Bayer Immuno 1 CA 15-3 assay and compared assay performance to two manual tests. Results of the 10-day imprecision study of the Bayer Immuno 1 assay pooled across four evaluation sites and three lots of reagent produced total CV < or = 4%. Lot-to-lot reproducibility for 26 different lots of reagents and calibrators manufactured over a 2-year period was demonstrated (CV, 1.1%). Results for the Bayer Immuno 1 assay correlated well with the Biomira TRUQUANT BR 27.29 and Centocor CA 15-3 RIAs (r > or = 0.94). The upper limit of the reference interval for the Bayer Immuno 1 assay was 35.9 kilounits/L (35.9 units/mL); values were similar for all methods. Longitudinal monitoring of healthy women yielded assay values with an average CV of 11% and 21% for the Bayer Immuno 1 and Biomira assays, respectively. The Bayer Immuno 1 assay demonstrated the analytical features, intermethod correlation, and long-term performance characteristics that are essential for longitudinal monitoring of breast cancer patients.

Myoglobin clearance during continuous veno-venous hemofiltration with or without dialysis

The management of acute myoglobinuric renal failure, the major complication of rhabdomyolysis, continues to be a treatment dilemma for the clinician as limited therapeutic options are available. Previously, we have demonstrated that continuous arteriovenous hemofiltration (CAVH) is an effective technique for removing myoglobin in an animal model. In the present study, swine were administered four grams of equine myoglobin intravenously and underwent the continuous veno-venous hemofiltration (CVVH) procedure for six hours each. Animals were studied in each of the following groups: CVVH at a pump rate 100 ml/minute, CVVH at a pump rate 200 ml/minute and CVVH at a pump rate 100 ml/minute plus dialysis at a dialysate flow rate of one Liter/h. Once the filtering process was initiated there was a rapid and sustained production of ultrafiltrate in all groups. The amount of myoglobin excreted in the ultrafiltrate over the six-hour filtering period was 688, 948 and 570 mg which corresponded to 17, 24 and 14 percent of the administered dose, respectively, for the three treatments. In comparison to previous CAVH experiments, CVVH removed more circulating myoglobin and the addition of the dialysis component did not appear to improve removal. Based on these findings, it appears that the CVVH hemofiltration system is a viable option for the removal of systemic myoglobin.

Coronary angioplasty induces a systemic inflammatory response

C-reactive protein (CRP) levels increased more than sixfold above baseline when measured 48 hours after elective percutaneous transluminal coronary angioplasty (PTCA) in patients without underlying inflammatory conditions and did not change significantly in controls undergoing coronary angiography. Only 3 of the 42 PTCA patients had clinical restenosis and underwent target vessel revascularization during the 6-month follow-up, but 2 of the 3 had very high CRP levels 48 hours after the procedure.

Serum levels of prostate-specific antigen among Japanese-American and native Japanese men

BACKGROUND

Fourfold to sixfold higher prostate cancer rates in Japanese-American men in the United States compared with Japanese men in Japan have been cited to support a role for environmental risk factors in the etiology of the disease. To examine the hypothesis that part or all of the elevated prostate cancer rates in Japanese-American men may reflect more intensive prostate cancer screening in the United States than in Japan, we compared prostate-specific antigen (PSA) levels in community-based samples of serum from men without prostate cancer.

METHODS

Japanese-American men aged 40-85 years and native Japanese men aged 40-89 years with no history of prostate cancer provided sera, respectively, in the United States from March 1990 through March 1992 (n = 237) or in Japan from January 1992 through December 1993 (n = 3522). Age-specific PSA levels were used to estimate the prevalences of undetected prostate cancer in the two populations.

RESULTS

Age-specific mean PSA levels were significantly lower in Japanese-Americans than in native Japanese (two-sided P<.001). The prevalence of an elevated PSA level increased with age in both populations and exceeded 5% among men aged 60 years or more. Combined with data on prevalence of detected prostate cancer in the two populations, our data suggest that some 10.0% of Japanese-Americans aged 75 years have prostate cancer, with 31% of that fraction remaining undiagnosed. The corresponding estimates in Japan are a total cancer prevalence of 5.4%, of which 81% has not been detected clinically.

CONCLUSIONS

The total cancer prevalence ratio 10.0/5.4 = 1.9 (95% confidence interval = 1.5-2.3) in Japanese-American men compared with Japanese men in Japan suggests an increased risk for Japanese-American men, but of less magnitude than the fourfold to sixfold increase indicated by the incidence data.

The analysis of thebaine in urine for the detection of poppy seed consumption

The consumption of poppy seeds in various foods may lead to a positive opiate result in urine subjected to testing for drugs of abuse. As a natural constituent of poppy seeds, thebaine was investigated as a possible marker for poppy seed consumption. Poppy seeds were examined for opiate content by gas chromatography-ion trap mass spectrometry (GC-MS) after extraction with methanol. Urine samples spiked with thebaine and urine from subjects given 11 g of poppy seeds were tested for the presence of thebaine, codeine, and morphine. Street heroin, one morphine and one codeine tablet, and urine from individuals who had used heroin were also examined for thebaine. Urine specimens were screened by enzyme immunoassay (EMIT) and confirmed for thebaine by GC-MS using a solid-phase extraction method. The GC-MS assay showed a linear response over a range of 1-100 ng/mL and a limit of detection of 0.5 ng/mL. Thebaine was detectable in the urine of poppy seed eaters in concentrations ranging from 2 to 81 ng/mL. Because thebaine was absent in powdered drugs and the urine of true opiate drug users, thebaine is proposed as a direct marker for poppy seed use.

Association of soy and fiber consumption with the risk of endometrial cancer

The authors conducted a case-control study among the multi-ethnic population of Hawaii to examine the role of dietary soy, fiber, and related foods and nutrients on the risk of endometrial cancer. Endometrial cancer cases (n = 332) diagnosed between 1985 and 1993 were identified from the five main ethnic groups in the state (Japanese, Caucasian, Native Hawaiian, Filipino, and Chinese) through the rapid-reporting system of the Hawaii Tumor Registry. Population controls (n = 511) were selected randomly from lists of female Oahu residents and matched to cases on age (+/-2.5 years) and ethnicity. All subjects were interviewed using a diet history questionnaire that included over 250 food items. Non-dietary risk factors for endometrial cancer included nulliparity, never using oral contraceptives, fertility drug use, use of unopposed estrogens, a history of diabetes mellitus or hypertension, and a high Quetelet's index (kg/cm2). Energy intake from fat, but not from other sources, was positively associated with the risk of endometrial cancer. The authors also found a positive, monotonic relation of fat intake with the odds ratios for endometrial cancer after adjustment for energy intake. The consumption of fiber, but not starch, was inversely related to risk after adjustment for energy intake and other confounders. Similar inverse gradients in the odds ratios were obtained for crude fiber, non-starch polysaccharide, and dietary fiber. Sources of fiber, including cereal and vegetable and fruit fiber, were associated with a 29-46% reduction in risk for women in the highest quartiles of consumption. Vitamin A and possibly vitamin C, but not vitamin E, were also inversely associated with endometrial cancer, although trends were not strong. High consumption of soy products and other legumes was associated with a decreased risk of endometrial cancer (p for trend = 0.01; odds ratio = 0.46, 95% confidence interval 0.26-0.83) for the highest compared with the lowest quartile of soy intake. Similar reductions in risk were found for increased consumption of other sources of phytoestrogens such as whole grains, vegetables, fruits, and seaweeds. Ethnic-specific analyses were generally consistent with these results. The observed dietary associations appeared to be largely independent of other risk factors, although the effects of soy and legumes on risk were limited to women who were never pregnant or who had never used unopposed estrogens. These data suggest that plant-based diets low in calories from fat, high in fiber, and rich in legumes (especially soybeans), whole grain foods, vegetables, and fruits reduce the risk of endometrial cancer. These dietary associations may explain in part the reduced rates of uterine cancer in Asian countries compared with those in the United States.

Use of cardiac markers as assessed by outcomes analysis

OBJECTIVES

This article will describe the outcomes studies that have been performed or are needed in relation to biochemical markers in coronary artery diseases (CAD).

METHODS AND RESULTS

Studies in five major areas are reviewed: the need for emergency department (ED) chest pain centers and the role of cardiac markers; impact of cardiac marker testing frequency on length of stay (LOS); interpretation of cardiac troponins T and I for risk stratification of cardiac patients with unstable angina (UA); serum markers for determining the success of intravenous thrombolytic therapy following acute myocardial infarction (AMI), and its role in rescue percutaneous transluminal coronary angioplasty (PTCA); and need and criteria for implementation of new cardiac tests.

CONCLUSIONS

Chest pain centers reduce unnecessary admissions and costs for AMI rule outs. Laboratories must perform testing on a stat basis for rapid rule out of AMI. Stat testing will also result in a reduction in hospital LOS for patients who rule in for AMI. For UA patients, studies are needed to determine how results of cardiac markers can be used to improve cardiac outcomes. Serial measurements of myoglobin offer the earliest discrimination for successful reperfusion, and should be used if rescue PTCA becomes important therapeutically. New markers for early diagnosis are needed to complement tests such as myoglobin and CK-MB isoforms. Markers that assess early pathophysiologic events of AMI such as inflammation, thrombosis, and pre-necrosis ischemia have the most promise.

Detection and interpretation of lysergic acid diethylamide results by immunoassay screening of urine in various testing groups

A total of 2259 urine samples were assayed for lysergic acid diethylamide (LSD) using radioimmunoassay (RIA, Coat-a-Count, Diagnostics Products) and a premarket cloned enzyme donor immunoassay (CEDIA, Boehringer Mannheim). Urine samples were obtained from patients admitted to the emergency room, patients in drug rehabilitation programs, and adults and juveniles in criminal probation programs. An overall incidence of positive results was 0.80% for CEDIA (500-pg/mL cutoff) and 0.89% and 0.18% for RIA at cutoffs of 250 and 500 pg/mL, respectively. Of the CEDIA-positive samples, only 17 and 11% were positive by RIA at 250 and 500 pg/mL, respectively, whereas among RIA-positive samples, only 10% of those > 250 pg/mL and only 25% of those > 500 pg/mL were positive by CEDIA. Moreover, only 2 of 25 of samples positive by one of these screening assays were confirmed by gas chromatography-mass spectrometry (GC-MS). It is likely that discrepancies in results between immunoassays are due to differences in antibody specificities used to detect LSD metabolites. In addition, immunoassays may be more sensitive than GC-MS for detecting LSD use as current confirmation assays are targeted towards detection of the parent drug only. The interpretation of results for LSD analysis must be made with knowledge of the limitations for each assay.

Quantitative determination of theophylline by an automated chemiluminescent immunoassay in serum and plasma: comparison to other methods of analysis

A chemiluminescent immunoassay for theophylline in serum or plasma was developed for the Ciba Corning ACS: 180 automated analyzer. The assay has a limit of quantitation of 0.2 microgram/ml, with a range up to 40 micrograms/ml. The cross-reactivity to metabolites 1,3-dimethyluric acid 3-methylxanthine was 3.4% and 2.5%, respectively. Overall means of 101.0% and 97.8% were determined from dilution linearity and addition studies, respectively. When compared to a high-performance liquid chromatography (HPLC) method, a linear regression of ACS Theophylline = 0.996 (HPLC) + 0.35, r = 0.991, n = 93, was obtained. Similar results were obtained when the ACS assay was compared to other immunoassays. Precision (within-run and total coefficient of variation or CV) was < 6% in the therapeutic range (10-20 micrograms/ml). The performance data demonstrate that the ACS Theophylline assay provides an additional choice for the clinical measurement of the drug.

Smoking, alcohol use, dietary factors and risk of small intestinal adenocarcinoma

To investigate the role of tobacco and alcohol use and dietary factors in the etiology of small intestinal adenocarcinoma, we analyzed data from a large population-based case-control study of multi-site cancers conducted in Los Angeles County between 1975 and 1984. The present analysis included interview information on 36 small intestinal adenocarcinoma patients and 998 population controls. After adjusting for age and ethnicity, men who smoked more than 100 cigarettes during their lifetimes were at a non-significantly 3-fold increased risk for small intestinal adenocarcinoma; this association was substantially weaker in women. In men and women combined, a significant 3-fold increased risk in heavy drinkers (80+ g ethanol/day) relative to more moderate drinkers and non-drinkers was observed. Although frequent (>6 times vs. less than 2 times of intake a week) intake of foods rich in heterocyclic aromatic amines (based on the combined intake of fried bacon and ham, barbecued and/or smoked meat and smoked fish) was associated with a significant 4.5-fold increased risk of small intestinal adenocarcinoma in men; this association was not present in women. Based on 2 questions that provided a crude assessment of sugar intake, risk of small intestinal adenocarcinoma in men and women appeared to be associated with adding sugar regularly in coffee or tea and daily intake of non-diet carbonated soft drinks. When we computed total sugar intake from tea, coffee and non-diet carbonated soft drinks, there was a consistent and significant trend of increasing sugar intake and risk of small intestinal adenocarcinomas. Compared with the lowest intake level a day (<5 g), medium (5-25 g) and high intakes (>25 g) were associated with ORs of 2.5 and 3.8, respectively.

Smoking, alcohol use, dietary factors and risk of small intestinal adenocarcinoma

To investigate the role of tobacco and alcohol use and dietary factors in the etiology of small intestinal adenocarcinoma, we analyzed data from a large population-based case-control study of multi-site cancers conducted in Los Angeles County between 1975 and 1984. The present analysis included interview information on 36 small intestinal adenocarcinoma patients and 998 population controls. After adjusting for age and ethnicity, men who smoked more than 100 cigarettes during their lifetimes were at a non-significantly 3-fold increased risk for small intestinal adenocarcinoma; this association was substantially weaker in women. In men and women combined, a significant 3-fold increased risk in heavy drinkers (80+ g ethanol/day) relative to more moderate drinkers and non-drinkers was observed. Although frequent (>6 times vs. less than 2 times of intake a week) intake of foods rich in heterocyclic aromatic amines (based on the combined intake of fried bacon and ham, barbecued and/or smoked meat and smoked fish) was associated with a significant 4.5-fold increased risk of small intestinal adenocarcinoma in men; this association was not present in women. Based on 2 questions that provided a crude assessment of sugar intake, risk of small intestinal adenocarcinoma in men and women appeared to be associated with adding sugar regularly in coffee or tea and daily intake of non-diet carbonated soft drinks. When we computed total sugar intake from tea, coffee and non-diet carbonated soft drinks, there was a consistent and significant trend of increasing sugar intake and risk of small intestinal adenocarcinomas. Compared with the lowest intake level a day (<5 g), medium (5-25 g) and high intakes (>25 g) were associated with ORs of 2.5 and 3.8, respectively.

Impact of CK-MB testing policies on hospital length of stay and laboratory costs for patients with myocardial infarction or chest pain

We obtained data on hospital length of stay (LOS) and total laboratory charges for Medicare patients admitted to 82 hospitals in Massachusetts during 1994. Five Diagnosis Related Groups (DRGs) were selected: surviving acute myocardial infarction (AMI) with, and without, complications; AMI with death; angina pectoris; and chest pain. The hospitals were grouped according to their laboratory policies for testing CK-MB (e.g., frequency of assay runs; information obtained by telephone survey). The study was conducted to determine whether there was an association between turnaround times for results and LOS for cardiac DRGs. The mean LOS for AMIs with complication for 1513 patients admitted to 22 hospitals whose laboratories perform CK-MB testing once or twice daily was 8.4 days [95% confidence interval (CI): 8.2-8.7]. In contrast, the mean LOS for hospitals with CK-MB test policies of at least 3 runs daily or random-access stat was significantly (P <0.05) lower, 7.7 days (CI: 7.4-8.0 and 7.5-7.9, respectively). Overall laboratory charges were lower in the hospitals with shorter LOS. With one exception, there was no significant difference in LOS between patients with DRGs of angina pectoris or chest pain or other AMI DRGs. For AMI, a CK-MB testing policy that produces shorter turnaround times may be justified because of an association with reductions in LOS and overall laboratory costs.

Reducing the inappropriate utilization of clinical laboratory tests

Reimbursement policies for health-care services in Connecticut and the U.S. have gradually shifted towards fixed reimbursements through implementation of managed care. As a result, there is an increasing need by physicians and other care givers to reduce costs without compromising the quality of the care being delivered. The clinical laboratory is one area where significant cost reductions may be realized. More effective utilization can be accomplished with the elimination of panels of tests, such as the general chemistry profile, removal of antiquated tests or those that provide redundant information, judicious use of drug assays, acceptance of clinical practice guidelines, and use of reflex testing algorithms. Physicians should also focus more on prognostic indicators for disease prevention. Point-of-care testing devices which have higher costs than incremental central laboratory expenses should be used only if it reduces overall operating expenses, as assessed by outcomes analyses. New technologies such as DNA probes can substantially improve diagnostic efficiency. Physicians and clinical laboratories must collaborate to achieve more efficient utilization practices.