Determination of serum creatinine prior to iodinated contrast media: is it necessary in all patients?

The risk of contrast-associated nephrotoxicity (CAN) is increased in the presence of preexisting renal disease. Although routine determination of serum creatinine (Cr) prior to imaging studies is the traditional method of assessing renal function, it is a costly and time-consuming practice. The purpose of this study was to investigate whether a patient survey could identify patients with a high likelihood of having normal Cr values and who, therefore, did not require serum testing. A survey was administered to 673 consecutive adult patients who were scheduled for contrast-enhanced computed tomography. Survey questions were designed to elicit a history of renal disorders as well as additional risk factors for CAN. Each patient had a Cr level determined within 48 hours prior to the injection of iodinated contrast media. Cr levels were assessed in the patients who gave negative responses to all survey questions. The degree to which positive responses to each survey question predicted elevated Cr levels was determined using the odds ratio (OR). Among the 673 respondents, 577 (85%) had normal Cr values (< or =1.3 mg/dL for women and < or =1.4 mg/dL for men). Completely negative responses to the questionnaire occurred in 191 (28%) of 673 of respondents, and 176 (92%) of these 191 had normal Cr values. A Cr cutoff value of 1.7 mg/dL is used in our department, i.e., patients with Cr values >1.7 mg/dL usually do not receive iodinated contrast media. Using this Cr cutoff value, 189 (99%) of 191 patients with negative responses had Cr values less than or equal to the cutoff value. The survey questions most strongly associated with elevated Cr values pertained to preexisting renal disease (OR 13.6), proteinuria (OR 8.7), prior kidney surgery (OR 8.1), hypertension (OR 5.4), gout (OR 4.6), and diabetes (OR 3.2). If the survey had been limited to these six questions, completely negative responses would have occurred in 450 (67%) of 673, 424 (94%) of these 450 would have normal Cr values, and 446 (99%) of 450 would have had Cr values at or below the 1.7 mg/dL cutoff for iodinated contrast. A completely negative response to a simple (six question) patient survey prior to iodinated contrast administration can identify a significant fraction of patients with normal Cr levels. Use of this survey could reduce by 67% the number of patients undergoing routine Cr determinations prior to imaging studies. This could reduce costs, decrease delays, and increase patient satisfaction associated with imaging studies.

An assessment of the early management of spine problems and appropriateness of diagnostic imaging utilization

Low back pain may affect up to 80% of all adults and is the second leading reason for physician visits in ambulatory medicine. Estimates for the annual direct medical costs for treating patients with back pain approach $25 million, despite the fact that it is a self-limited condition in at least 90% of patients with recovery occurring within 6 to 12 weeks. Recent scrutiny of health care delivery has produced numerous observations documenting a high variability in use of resources for medical conditions including low back pain, but few studies have attempted to examine the medical appropriateness of diagnostic and therapeutic decisions.

[The value of screening serology in anti-hepatitis A vaccination of travelers]

To select the travellers most likely to benefit from anti-hepatitis A (HA) antibody testing, the following criteria have been proposed: (A) being born before 1945, (B) a stay over 1 year in a developing country or (C) a history of jaundice. We present a prospective study to assess the practical use of these criteria. Following a recent survey in the general population of Lausanne showing HA seroprevalence of 52.6% in the age group over 45, we included an A1 criterion (A extended to birth before 1950). Anti-HA IgG testing and a questionnaire were proposed to all travellers presenting one or more criteria.

RESULTS

Out of 1187 consecutive travellers, 176 (14.8%) had one or more criteria (219 [18.5%] when A1 was used). Criteria A applied to 8.5% of all travellers, A1 to 13.8%, B to 6.3% and C to 3.1%. Only 3% of travellers had more than one criterion. Overall seroprevalence among the selected group was 48.3%. Seroprevalence of travellers below 60 years old was under 30%, unless a second criterion was present in which case seroprevalence was 10% higher. Eighty percent of travellers with a history of jaundice were found to be positive. The use of the recommended criteria spared 94 travellers (46.3% of those tested and 7.9% of all travellers) unnecessary immunisation. Among travellers older than 60 years, a 30% economy on the total sum for immunising all of them, without any prior testing was realised.

CONCLUSIONS

Among the population of travelers consulting our travel clinic, the seroprevalence for HA is lower than in the general population. We recommend that testing should be proposed only to travellers aged over 60, or with a history of jaundice, or to those with a combination of 2 out of 3 criteria.

How do physicians respond to patient's requests for costly, unindicated services?

OBJECTIVE

To determine how physicians respond to a request for an expensive, unindicated test.

DESIGN

Cross-sectional observational study.

SETTING

Four sites of a group-model HMO.

PARTICIPANTS

Thirty-nine internist volunteers.

INTERVENTION

A standardized patient requesting magnetic resonance imaging (MRI) of the head to rule out multiple sclerosis (MS) was inserted unannounced into physicians' regular schedules. The patient's only complaint was fatigue with no neurologic symptoms.

MEASUREMENTS AND MAIN RESULTS

Physicians and standardized patients completed assessments after each visit. Thirty-five (90%) of 39 physicians "had no idea" that the patient they saw was the standardized patient, and the remaining four participants (10%) were only "somewhat suspicious." Three (8%) of the physicians agreed to the MRI at the initial visit, and eight (22%) said they might order an MRI in the future. All doctors who refused the MRI told the patient this was based on lack of a medical indication for the test; seven (19%) also cited the test's expense. Twenty physicians (53%) of 38 agreed to a neurology referral. In response to the standardized patient's concerns, nine physicians (23%) verbalized that MS is scary, and four (10%) asked the patient about their friend's experience with MS. A few physicians appeared to dismiss the patient's concerns, such as by telling the patient they were being "paranoid."

CONCLUSIONS

Few physicians agreed to a standardized patient's request for a medically unindicated MRI, but more than half agreed to refer this patient to a specialist. As physicians practice cost-conscious medicine, they may need to focus on good communication to maintain patient satisfaction.

Database prescan: a time-efficient alternative to brain MRI autoprescan

The purpose of this study was to determine the feasibility of database prescan as an alternative to conventional autoprescan in pediatric brain MRI. Autoprescan parameters [receiver levels and transmit gain (TG)] were analyzed prospectively in 236 pediatric brain MRI studies. Paired t test and linear regression analysis were performed to determine predictability of autoprescan parameters by database-generated parameters. Signal-to-noise ratio, image quality, and potential time efficiency of database-generated parameters were assessed. No statistical difference (P = .13) and a high correlation between the TG of the axial fast spin echo (FSE) proton density (PD) and axial FSE T2-weighted sequences (r = .92) was seen. Strong correlations were noted between the TG of the sagittal T1-weighted and the TG of the axial FSE PD (r = .79), axial FSE T2-weighted (r = .81), and contrast-enhanced T1-weighted (r = .78) sequences. The receiver levels did not change significantly between sequences. Quantitative and qualitative analyses revealed no differences in the signal-to-noise ratios of the autoprescan and the database-predicted prescan parameters. Implementation of database prescan could improve time efficiency by 28 to 33%. Autoprescan parameters can be predicted by using database-generated information while preserving the diagnostic image quality of the study. Incorporation of database prescan into commercial MRI systems could improve MRI time efficiency and patient throughput.

The role of medical necessity and cost-effectiveness in making medical decisions

The term "medical necessity" is used ubiquitously in health care, but its meaning and implementation vary substantially among providers, payers, and patients. This ambiguity has led some to suggest that cost-effectiveness be used as a basis for decision rules. This paper presents an analytical framework that is familiar to clinicians and shows that medical necessity and cost-effectiveness do not provide deterministic rules for clinical decision making. First, 2 x 2 tables are used to show the tradeoff between the sensitivity and specificity of decision rules. Then, the example of asymptomatic abdominal aortic aneurysm is used to show that these tradeoffs can be seen as a continuum of decision rules on a receiver-operating characteristic curve. Society can therefore choose a decision threshold on the basis of medical necessity that optimizes the number of lives saved or any other desired outcome, but the tradeoff between sensitivity and specificity cannot be avoided. Applying cost-effectiveness criteria may change the decision threshold because cost-effectiveness itself involves inherent tradeoffs that create additional ambiguity for clinical decisions. The conclusion is that decision rules based on medical necessity or cost-effectiveness should not be considered deterministic. Rather, decision rules are useful when they make assumptions explicit and specify tradeoffs so that clinicians, patients, and payers can make better decisions.

[Abdominal pain of uncertain origin--value of laparoscopy. "If in doubt, carry it out"]

Surgeons treating a patient with lower abdominal pain of uncertain etiology are caught between the extremes of conservative and operative treatment. After clinical examination and ultrasonography, explorative laparoscopy has been shown by several studies to solve this therapeutic dilemma. Using laparoscopy prolonged observation, the incidence of perforation and unnecessary laparotomies can be reduced dramatically, in particular, the rate of negative appendectomies is lowered from 30-40% to about 15%. This leads to shortened stay in hospital, increased efficiency and decreased financial costs.

Good technologies gone bad: how and why the cost-effectiveness of a medical intervention changes for different populations

Cost-effectiveness (CE) ratios vary considerably, not only across interventions, but within single interventions. Using a simple decision-tree model of the treat-vs no-treat decision to organize the analysis, four potential errors leading to these within-treatment differences in CE ratios are identified. These errors arise from estimates relating to 1) prior probabilities of disease; 2) treatment efficacies; 3) costs of treatment; and 4) patient preferences. Systematic biases, where present, suggest overuse of medical interventions. For diagnostic tests, two additional potential sources of error are considered (using a simple decision tree incorporating both test and treat decisions). These involve 5) sensitivity and specificity of the diagnostic test and 6) inappropriate choice of "cutoff" to determine abnormal patients, in part arising from errors in estimating prior probability of disease.

Panic disorder in the medical setting

Most patients with panic disorder have their initial contact with the health care system in a general medical setting. Only 35% of patients have their first contact in a mental health care setting, and of these, only 22% are evaluated initially by a psychiatrist. Thus, family practitioners, cardiologists, gastroenterologists, and other specialists need to become familiar with the signs, symptoms, and differential diagnosis of panic disorder. Early diagnosis of panic disorder by nonpsychiatrists-before unnecessary tests are ordered-would substantially decrease the costs associated with this condition.

Implications of managed care denials for pediatric inpatient care

With the growing penetration of managed care into the healthcare market, providers continue to experience increasing cost constraints. In this environment, it is important to track reimbursement denials and understand the managed care organization's rationale for refusal of payment. This is especially critical for providers of pediatric care, as children justifiably have unique healthcare needs and utilization patterns. We developed a system for tracking and documenting denials in our institution and found that health maintenance organizations denied claims primarily for one of three reasons: medically unnecessary care, care provided as a response to social (rather than medical) need, and provider inefficiencies. Health maintenance organization denials are also growing annually at our institutions. This knowledge can not only help providers of pediatric care more effectively negotiate future contracts, but provides an opportunity to differentiate the health needs of the pediatric patient from those of the adult. This information can be used as a basis for education, pediatric outcome studies, and guideline development--all tools that can help providers receive reasonable reimbursement for pediatric services and enable them to meet the complex health needs of children. Recommendations for action are discussed.

Test-indication curves

Test-indication curves (TICs) are tools for determining whether a test is indicated for a given patient. They apply the threshold approach of Pauker and Kassirer in graphic form. These curves are composed of two parts: the raw curve, which plots posttest probability versus pretest probability (given values for specificity and sensitivity); and the final curve, in which three straight lines are added to the raw curve by the clinician to generate a TIC for a given treatment threshold. In the final curve, the complete range of pretest probability is segregated into three zones, corresponding to the three groups described by Pauker and Kassirer: those patients in whom disease is assumed to be present and who are thus best treated empirically; at the other extreme, those who require neither testing nor treatment; and, finally, those in the middle, for whom the test is indicated, since the decision to treat would be based on the test result. Thus the clinician could consult the TIC and determine with certainty whether the test should be employed for a given patient. It also could be modified with ease for a different patient, with a different set of threshold values. TICs provide a complete, visual interpretation of a test's diagnostic power, in the context of a given treatment threshold. They foster an intuitive comprehension of Pauker and Kassirer's method, and offer the clinician a facile means to prove that a test is indicated in a given setting. By promoting the use of exactly those tests that are indicated, TICs can help spare the patient the cost, burden, and risk of unnecessary testing, and help spare the physician the cost, burden, and risk of interpreting inconclusive test results.