Assessing the impact of patient self-selection on the costs to treat latent tuberculosis infection (LTBI) with isoniazid and transitional rifampin.

RATIONALE, AIMS AND

OBJECTIVES

This article examines costs to treat latent tuberculosis infection (LTBI) in an urban clinic population and highlights the potential effectiveness of an alternative transitional treatment regimen.

METHODS

Patients who experienced side effects on the gold standard of 9 months of isoniazid (9INH) were either continued on isoniazid or transitioned to 4 months of rifampin (4RIF). I use multilevel Tobit models with selection to analyse whether transitioning to 4RIF is less costly than remaining on 9INH among patients experiencing side effects.

RESULTS

Results reveal that self-selection is present in this clinic data. Using an ordered probit parametric selection rule to account for selection, I find transitioning patients to 4RIF costs significantly less than continuing on 9INH. This result is especially sensitive to selection: not controlling for selection demonstrates that patients transitioning to 4RIF actually cost significantly more to treat. Post hoc analysis revealed that switching to 4RIF significantly reduced the dropout probability among these patients.

CONCLUSION

Future work should more carefully assess the clinical attributes, including effectiveness, of treatment with 9INH and transitional 4RIF as alternative treatment for LTBI.