Hospital and Brown University, Providence, RI PURPOSE: We analyzed a representative sample of 19,058 visits from the 1998 National Ambulatory Medical Care Survey (NAMCS) to examine the frequency that physicians reported counseling patients about their diet. METHODS: Patients with diabetes, coronary heart disease (CHD), hyperlipidemia, obesity, and hypertension were identified using a combination of visit codes, diagnoses and current medications from forms completed by physicians after patient encounters. Independent determinants of diet counseling were evaluated using multiple logistic regression. RESULTS: Overall, diet counseling was performed during 12.3% of all visits and was more common among patients who were middle-aged (45 ± 64 years) (13.4% vs. 11.8% for other age groups; p < .05) nonwhite (14.2% vs. 12.3%; p < .01), presenting for routine chronic care or a routine physical vs. acute care (14.7% and 18.5%, respectively: vs. 9.7%; p < .01), for patients with diabetes (33.8%), obesity (55.8%), hyperlipidemia (36.2%), and hypertension (36.%) (p < .01 for all comparisons), if the physician was a primary care provider (22.0%), cardiologist (27.0%) or ostetrician/gynecologist (16.0%) vs. other providers (5.8%, p < .001), and if the patient was also counseled about physical activity (67.5% vs. 11.5%; p < .001). These effects persisted after multiple logistic regression analyses controlling for potential confounders. Gender, coronary heart disease history, region of the country and insurance type were not associated with diet counseling. CONCLUSION: In conclusion, health care providers primarily use diet counseling as a treatment for diet-related illnesses, rather than as primary prevention, where it was noted that fewer than 1 in 5 patients were counseled about their diet during routine physicals. . This testing is typically with a sensitive activated partial thromboplastin time (aPTT) and dilute Russel viper venom time (dRVVT), followed by mixing studies and confirmatory tests. With decision analysis, we investigated the optimal testing strategy for detecting LA in three clinical settings. METHODS: A decision-tree was constructed with 12 strategies, using a combination of aPTT and dRVVT with confirmatory tests, tissue thromboplastin time (TTI), platelet neutralizing procedures, and mixing studies. Probabilities of adverse events, utilities of these events, and costs were obtained from a literature review. Sensitivity and specificity of each strategy was calculated by testing 90 healthy people and 77 patients, with true positives defined as per the algorithm recommended by the International Society on Thrombosis and Haemostasis. RESULTS: For healthy people with a prolonged aPTT, the optimal strategy is not to test for LA and assume that no patient has LA. For patients with systemic lupus erythematosus (SLE), it is cost saving to test with TTI alone if the cost of the test is less than $13 (base case -$9), or if the prevalence of LA in the population is > 33% (base case-35%). For patients with past thrombosis or fetal loss, it is cost saving to avoid testing and assume no patient has LA, or to use TTI alone if the expected prevalence of LA is > 33% (base case-9%). CONCLUSION: It is optimal in healthy people and in those with a low likelihood of LA to avoid testing and to assume that these patients do not have LA. However, for patients with SLE, or for patients with past thromboses and a high likelihood of LA, TTI is a cost saving test. These results suggest that the current strategy for detecting LA needs to be modified.