Background:Disseminated infection with Histoplasma capsulatum and Mycobacterium avium complex (MAC) in patients with AIDS are frequently difficult to distinguish clinically.Methods: We retrospectively compared demographic information, other opportunistic infections, medications, symptoms, physical examination findings and laboratory parameters at the time of hospital presentation for 32 patients with culture documented disseminated histoplasmosis and 58 patients with disseminated MAC infection.Results: Positive predictors of histoplasma infection by univariate analysis included lactate dehydrogenase level, white blood cell (WBC) count, platelet count, alkaline phosphatase level, and CD4 cell count. By multivariate logistic regression analysis, those characteristics that remained significant included a lactate dehydrogenase value ≥500 U/L (risk ratio [RR], 42; 95% confidence interval [CI], 18.53-97.5; p < .001), alkaline phosphatase ≤300 U/L (RR, 9.35; 95% CI, 2.61-33.48; p = .008), WBC ≤4.5 × 106/L (RR, 21.29; 95% CI, 6.79-66.75; p = .008), and CD4 cell count (RR, 0.958; 95% CI, 0.946-0.971; p = .001).Conclusions: A predictive model for distinguishing disseminated histoplasmosis from MAC infection was developed using lactate dehydrogenase and alkaline phosphatase levels as well as WBC count. This model had a sensitivity of 83%, a specificity of 91%, and a misclassification rate of 13%.
Address correspondence and reprint requests to Richard J. Hamill, Section of Infectious Diseases (111G), Veterans Affairs Medical Center, 2002 Holcombe Boulevard, Houston, TX 77030-4211, U.S.A.; email: firstname.lastname@example.org.
A portion of this project was completed in partial fulfillment of the requirements for a Master of Science degree for E. A. Vanden Heuvel. The data used in this paper were previously presented in part at the 34th Interscience Conference on Antimicrobial Agents and Chemotherapy, Orlando, Florida, U.S.A., October 7, 1994.
Some patients in this study participated in treatment trials supported by the National Institutes of Allergy and Infectious Diseases Mycoses Study Group (contract #NO1-Al-15082).
C. E. Lacke is currently affiliated with Section of Infectious Diseases, Veterans Affairs Medical Center, Houston, Texas, U.S.A.; E. A. Vanden Heuvel is currently affiliated with Lyndon Baines Johnson Hospital, Houston, Texas, U.S.A.; and S. A. Spindel is now in private practice in Oregon, U.S.A.
Manuscript received October 21, 1999; accepted February 4, 2000.
© 2000 Lippincott Williams & Wilkins, Inc.