Utilization of lipid-laden macrophage index in evaluation of aerodigestive disorders

The utility of the lipid-laden macrophage index (LLMI) in the evaluation of airway inflammatory processes remains controversial. There is a paucity of normative data in both pediatric and adult populations, and there is wide variability in the reported cases. The goal of this project was to review the LLMI levels in a large series of patients with a wide range of well-documented pulmonary and airway diseases (cystic fibrosis, aspiration, tracheo/bronchomalacia, recurrent pneumonia, asthma, immunosuppressed conditions, and laryngeal clefts) to develop a better understanding of the clinical utility of the LLMI.

This study is a retrospective analysis of patients who underwent initial bronchoscopy with broncheoalveolar lavage (BAL) and had specimens sent for determination of LLMI. This study was performed at a major pediatric tertiary care medical center from April 12, 2006 to July 13, 2009.

Medical charts were reviewed for major diagnoses, indications for bronchoscopy, the side of lung (right versus left), documented aspiration, suspected aspiration, neutrophil counts, and patient age. These qualitative and quantitative variables were considered in relation to the LLMI.

The cohort of patients examined were 4.9 ± 4.3 years (4 days to 18 years of age). Forty-two percent were female and 58% were male. The highest median LLMI was in immunocompromised patients with a median of 78. Recurrent pneumonia, aspiration, tracheo/bronchomalacia, and cystic fibrosis had median LLMI levels of 55, 49, 40, and 50, respectively. There was a wide range of LLMI within each primary diagnosis. There was no significant correlation between neutrophils percentage in the BAL and LLMI. There were no significant differences between BAL specimens obtained from the right or left side.

To our knowledge, this is the largest series of patients reported in the literature to have an LLMI compared with underlying diagnoses. Based on our data and analyses, there is wide variability between the range of LLMI and the primary diagnosis. As such, the diagnostic utility of the LLMI is limited and should be interpreted with caution.