Table 1.
Survival Analysis in Our Tulane Idiopathic Pulmonary Fibrosis Cohort
| Clinical Characteristics | |||
|---|---|---|---|
| Age (yr), median (IQR) | 69.6 (64.5–75.7) | ||
| Sex: male, n (%) | 129 (70.1) | ||
| FVC (% predicted), median (IQR) | 69.0 (55.7–81.0) | ||
| DlCO (% predicted), median (IQR) | 45 (37.5–55.5) | ||
| MPV (femtoliters), median (IQR) | 9.90 (8.90–10.6) | ||
| Platelet count (per μl), median (IQR) | 229 (190–264) | ||
| Monocyte count (×109 per L), median (IQR) | 0.670 (0.55–0.84) | ||
| Cox Proportional Hazards Regression Model | |||
|---|---|---|---|
| P value | Hazard Ratio (95% CI) | ||
| Univariate Analysis | Age, yr | 0.006 | 1.037 (1.010–1.064) |
| Sex (male compared with female) | 0.162 | 1.446 (0.863–2.425) | |
| FVC (% predicted) | <0.001 | 0.970 (0.957–0.984) | |
| DlCO (% predicted) | <0.001 | 0.961 (0.944–0.979) | |
| MPV | 0.042 | 1.210 (1.007–1.453) | |
| Platelet count | 0.114 | 1.003 (0.999–1.006) | |
| Monocyte count | 0.502 | 1.435 (0.500–4.116) | |
| Multivariate Analysis 1 | Age, yr | 0.467 | 1.011 (0.982–1.040) |
| Sex (male compared with female) | 0.236 | 1.467 (0.779–2.763) | |
| FVC (% predicted) | 0.031 | 0.982 (0.966–0.998) | |
| DlCO (% predicted) | 0.002 | 0.969 (0.950–0.989) | |
| MPV | 0.031 | 1.235 (1.020–1.496) | |
| Multivariate Analysis 2 | Age, yr | 0.172 | 1.020 (0.992–1.048) |
| Sex (male compared with female) | 0.477 | 1.245 (0.680–2.282) | |
| FVC (% predicted) | 0.007 | 0.980 (0.965–0.994) | |
| DlCO (% predicted) | 0.009 | 0.976 (0.959–0.994) | |
| Platelet count | 0.147 | 1.003 (0.999–1.007) | |
| Multivariate Analysis 3 | Age, yr | 0.454 | 1.011 (0.982–1.040) |
| Sex (male compared with female) | 0.122 | 1.670 (0.872–3.200) | |
| FVC (% predicted) | 0.026 | 0.982 (0.967–0.998) | |
| DlCO (% predicted) | 0.003 | 0.971 (0.952–0.990) | |
| MPV | 0.012 | 1.291 (1.056–1.577) | |
| Platelet count | 0.075 | 1.004 (1.000–1.009) | |
Definition of abbreviations: CI = confidence interval; IQR = interquartile range; MPV = mean platelet volume.
Patients with IPF followed at Tulane Medical Center or University Medical Center New Orleans were enrolled in this study (N = 184). The diagnosis of IPF was made according to the international guideline (10).
Data on age, sex, and platelet count were available from all 184 patients. Data on FVC, DlCO, MPV, and monocyte count were available from 177, 169, 165, and 167 patients, respectively.
We performed a univariate analysis with variables that have been shown to be associated with survival in multiple studies, then performed a multivariate analysis with variables with P < 0.20 in univariate analysis.
Univariate analysis revealed that higher MPV (but not higher platelet count) was significantly associated with worse lung transplant–free survival (P = 0.042; hazard ratio, 1.210; 95% CI, 1.007–1.453).
Multivariate analysis revealed that higher MPV (but not higher platelet count) was significantly associated with worse lung transplant–free survival, independent of age, sex, FVC, and DlCO (P = 0.031; hazard ratio, 1.235; 95% CI, 1.020–1.496) (multivariate analysis 1 and 2). Moreover, higher MPV was significantly associated with worse lung transplant–free survival, independent of age, sex, FVC, DlCO, and platelet count (P = 0.012; hazard ratio, 1.291; 95% CI, 1.056–1.577) (multivariate analysis 3).