Accuracy of Medicare claims-based diagnosis of acute myocardial infarction: estimating positive predictive value on the basis of review of hospital records

Background

Many cardiovascular epidemiologic studies rely on diagnosis codes in health care claims databases. Despite important changes in the care and diagnosis of acute myocardial infarction (AMI), the validity of hospital discharge diagnosis codes for AMI in the US Medicare system has not been recently examined. Our objective was to examine the accuracy of International Classification of Diseases—ninth revision—Clinical Modifications (ICD-9-CM) discharge diagnosis codes and diagnosis-related groups (DRG) codes for AMI in a Medicare claims database.

Methods

We sampled hospitalization episodes from Medicare beneficiaries in Pennsylvania during 1999, 2000, or both. We used Medicare data to identify patients with hospitalizations containing indicators of AMI (ICD-9-CM diagnosis codes 410.X0 and 410.X1 or DRG codes 121, 122, and 123). Hospital records for these episodes were reviewed by trained abstractors using World Health Organization criteria for diagnosing AMI. We then calculated the positive predictive value of Medicare claims-based definitions of AMI.

Results

Of 2200 hospitalization episodes with Medicare diagnosis codes suggestive of AMI, 2022 hospital records (91.9%) were obtained. The positive predictive value for a primary Medicare claims-based definition was 94.1% (95% CI, 93.0%-95.2%). Positive predictive values for alternative claims-based definitions ranged slightly, with the definition including DRG codes and length-of-stay restrictions yielding the highest positive predictive value, 95.4% (95% CI, 94.3%-96.4%). Subjects with a history of myocardial infarction had a significantly lower positive predictive value than subjects without a history of myocardial infarction (88.1% vs 94.6%, P <.001).

Conclusions

In this study, we observed high positive predictive values for a Medicare claims-based diagnosis of AMI and a diagnosis based on structured hospital record review.     

Angiotensin-converting enzyme insertion/deletion genotype is associated with the activities of plasma coagulation factor VII and X independent of triglyceride metabolism

BACKGROUND: The D allele of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism and coagulation activity play important roles in cardiovascular events, however, the precise association between these two risk factors remains unclear. METHODS: We identified the ACE I/D genotype and measured the plasma coagulation factor VII and X (FVII and FX) activities and serum lipids in 172 patients (110 men and 62 women, mean age 56.7+/-13.3 years) undergoing coronary angiography. RESULTS: The frequency of the D allele was significantly higher in those with a history of myocardial infarction (MI) than in those with normal coronary arteries, but there was no significant association between FVII and FX activities and the stage of coronary disease. Plasma coagulation factor VII and FX activities were significantly lower in the DD genotype (n=42) than in the II genotype (n=67, P<0.001 and P<0.001, respectively) or the ID genotype (n=63, P<0.01 and P<0.05, respectively). The association of the ACE D allele with lower activities of FVII and FX was also seen in patients with coronary artery disease (CAD). There was a significant association between serum triglyceride levels with FVII and FX, but not with the ACE I/D genotype. CONCLUSION: We concluded that the ACE I/D polymorphism may contribute more to the onset of MI than the activities of FVII and FX and that the ACE D allele might be associated with lower plasma activities of FVII and FX. The potential link between ACE I/D polymorphism and the plasma activities of FVII and FX is probably independent of triglyceride metabolism.     

Nonalcoholic fatty liver disease in Japanese patients with severe obesity who received laparoscopic Roux-en-Y gastric bypass surgery (LRYGB) in comparison to non-Japanese patients

Background. The number of patients with morbid obesity is increasing worldwide. However, the prevalence of morbid obesity is still low in Japan, and therefore few systematic investigations of liver dysfunction in this population have so far been carried out. This study aimed to investigate the clinical characteristics in severe obese Japanese patients undergoing laparoscopic Roux-en-Y gastric bypass surgery (LRYGB). Methods. Eighty-four patients with severe obesity, including 61 Japanese and 23 non-Japanese patients, were analyzed. Results. The mean body mass index (BMI) was 43.7 ± 7.8 kg/m², and there was no difference between Japanese and non-Japanese patients. Nonalcoholic fatty liver disease (NAFLD) was observed in 45/59 (76.2%) of the Japanese patients. Although there were no differences in the BMI and body weight, serum ALT was higher in Japanese patients in comparison to non-Japanese patients (P < 0.05). The indices for insulin resistance were significantly higher in the Japanese patients in comparison to non-Japanese patients (P < 0.01). The liver/spleen computed tomography (CT) ratios were lower in Japanese patients (P < 0.05). The laboratory data and BMI significantly improved at 1 year after LRYGB in both groups. Conclusions. Racial difference may exist difference may exist in NAFLD in patients with severe obesity. When the BMI is similar, liver dysfunction among Japanese patients with severe obesity tends to be higher than in non-Japanese patients. Japanese patients with severe obesity must therefore reduce their body weight to a greater degree in comparison to non-Japanese patients with the same BMI. LRYGB can achieve effective weight control and lower ALT levels in Japanese patients with severe obesity.     

Coronary stent implantation in patients with a single coronary artery--a report of 3 cases

An isolated single coronary artery is a rare congenital anomaly and a cause of cardiac ischemia, congestive heart failure, and sudden cardiac death. Reported here are 3 cases of single coronary artery with acute myocardial infarction in which coronary stenting was performed. Also reported are the coronary blood flow patterns of the right coronary artery arising from the single left coronary artery.     

Infective endocarditis caused by lactobacillus

Lactobacillus (LB) is a gram-positive rod-shaped bacterium that inhabits the oral cavity, gastrointestinal tract, vagina and nasal cavity. Although LB plays a role in the prevention of infections caused by pathogenic bacteria, it causes some critical infectious diseases such as infective endocarditis (IE). IE due to LB is rare; however, early diagnosis and early treatment are important because of its high mortality rate. We report the onset of IE after otologic treatment in a heavy drinker of alcohol, the second case of IE due to LB in Japan.     

Combination Analysis in Genetic Polymorphisms of Drug-Metabolizing Enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A5 in the Japanese Population

The Cytochrome P450 is the major enzyme involved in drug metabolism. CYP enzymes are responsible for the metabolism of most clinically used drugs. Individual variability in CYP activity is one important factor that contributes to drug therapy failure. We have developed a new straightforward TaqMan PCR genotyping assay to investigate the prevalence of the most common allelic variants of polymorphic CYP enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A5 in the Japanese population. Moreover, we focused on the combination of each genotype for clinical treatment. The genotype analysis identified a total of 139 out of 483 genotype combinations of five genes in the 1,003 Japanese subjects. According to our results, most of subjects seemed to require dose modification during clinical treatment. In the near future, modifications should be considered based on the individual patient genotype of each treatment.