Do the number and volume of surgical lung biopsies influence the diagnostic yield in interstitial lung disease? A propensity score analysis.

Introduction: Our objective was to evaluate whether the number and volume of surgical lung biopsies (SLB) influence the diagnosis of diffuse interstitial lung disease (ILD).

Methods: Retrospective study of SLB for suspected ILD in patients from the Mayo Clinic from January 2002 to January 2010. Data were collected in the institution and analyzed.

Results: 311 patients were studied. Mean number of biopsies was 2.05 (SD 0.6); 1 biopsy in 50 (16%), 2 in 198 (63.7%), 3 in 59 (19%) and 4 in 4 (1.3%). Histopathologic diagnosis was: definitive (specific): 232 (74.6%), descriptive (non-specific): 76 (24.4%), no diagnosis: 3 (1%). After excluding patients without diagnosis (n=3), there were 50 patients with only 1 biopsy, 196 with 2 and 62 with 3 or 4; the definitive diagnostic yield was similar in all 3 groups (37/50; 74%, 150/196; 77%, and 45/62; 73%) (Chi-square, p value 0.8). The propensity score analysis between patients with 1 SLB and patients with more than 1 SLB also showed no difference in diagnostic yield. Regarding the volume of biopsies, mean total volume was 34.4 cm(3) (SD 46): 41.2 cm(3) (3 cases) in patients with no diagnosis; 33.6 cm(3) (232 cases, SD 47) in patients with specific diagnosis; and 36.6 cm(3) (76 cases, SD 44) in patients with descriptive diagnosis. Biopsy volume had no influence on histopathology yield (ANOVA, p value .8).

Conclusions: The number and volume of the biopsy specimens in SLB did not seem to influence diagnosis. Based on our results, we believe a single sample from a representative area may be sufficient for diagnosis. Randomized prospective trials should be performed to optimize SLB for ILD.