Nonspecific interstitial pneumonia: survival is influenced by the underlying cause.

Idiopathic, nonspecific interstitial pneumonia (NSIP) is most often associated with various clinical disorders, including connective tissue diseases (CTDs) and chronic hypersensitivity pneumonitis (cHP). Emerging evidence also suggests that "idiopathic" NSIP may be the lung manifestation of undifferentiated CTD (UCTD). However, whether or not NSIP outcome is influenced by the underlying cause remains uncertain. This retrospective study included 127 biopsy-proven NSIP patients (65 women, mean ± sd age 55 ± 12 years). Survivals were estimated using a Kaplan-Meier curve and compared using the log-rank test. Multivariate analyses were based on a Cox model. 15 (11.8%) patients had cHP, 29 (22.8%) had CTD, 32 (25.2%) satisfied the Kinder criteria for UCTD and 51 (40.1%) had idiopathic NSIP. At the end of follow-up (mean ± sd 64 ± 54 months), a difference in survival was observed between aetiological groups (p=0.002). Survival was better for UCTD than for idiopathic NSIP (p=0.020) and similar to that observed for CTD. cHP survival tended to be poorer than that of idiopathic NSIP (p=0.087) and was an independent predictor of mortality (hazard ratio 2.17, 95% CI 1.05-4.47; p=0.035). NSIP outcome is influenced by its cause. cHP exhibits the highest mortality. UCTD does not differ from CTD supporting the concept of autoimmune NSIP, with a prognosis that is better than that of idiopathic NSIP.

Prognostic relevance of histological variants in nonspecific interstitial pneumonia.

AIMS: Although histological non-specific interstitial pneumonia (NSIP) is concisely defined, overlap with other patterns is described. While most frequently idiopathic, NSIP is seen in various clinical contexts such as connective tissue diseases (CTDs) and chronic hypersensitivity pneumonitis (cHP). This study was designed to determine if NSIP could be separated into subgroups based on minor histological features and to correlate these subgroups with clinical associations and survival. METHODS AND RESULTS: One hundred and thirty-six patients with biopsy-proven NSIP were included [clinical diagnosis: CTDs (23%), cHP (12%), idiopathic (65%)]. In addition to the agreed NSIP criteria, seven subgroups were identified: essential NSIP and six overlap subgroups according to superimposed minor histological features. Interobserver concordance resulted in the following consensus: essential NSIP (36%), usual interstitial pneumonia (UIP) overlap (26%), cHP overlap (10%), organizing pneumonia (OP) overlap (6%), organizing diffuse alveolar damage (DAD) overlap (10%), desquamative interstitial pneumonia overlap (7%) and lymphoid interstitial pneumonia overlap (2%). OP overlap was associated with CTDs (P = 0.04) and cHP overlap with a cHP clinical diagnosis (P = 0.02). Survival was different between subgroups (P = 0.0002). Organizing DAD overlap exhibited poorer survival at 5 years (32%), followed by UIP overlap (57%). Independent predictors of mortality were organizing DAD overlap (HR = 4.99, 95% CI = 2.15-11.58, P = 0.0002), UIP overlap (HR = 2.11, 95% CI = 1.12-3.99, P = 0.02) and a clinical diagnosis of cHP (HR = 2.17, 95% CI = 1.05-4.47, P = 0.035). CONCLUSIONS: Non-specific interstitial pneumonia subdivision into pathological subgroups is clinically relevant from a prognostic and causal perspective.