Pulmonary (99m)Tc-DTPA aerosol clearance and survival in usual interstitial pneumonia (UIP).
BACKGROUND
Clearance of inhaled technetium 99m-labelled diethylenetriamine penta-acetic acid ((99m)Tc-DTPA) from the lungs is a potential indicator of disease progression in patients with idiopathic pulmonary fibrosis (IPF).


METHODS
We prospectively analysed the usefulness of this technique for predicting survival in 106 non-smoking patients with usual interstitial pneumonia (UIP) pattern IPF diagnosed by high resolution CT (HRCT) scanning or histological examination (M/F 65/41, mean (SD) age 61 (11) years). DTPA clearance was analysed according to both mono-exponential and bi-exponential models. Half times for the fast (t(0.5)F) and slow (t(0.5)S) components of clearance, the percentage contribution of the fast component (fF), and half time for mono-exponential approximation to the early part of the clearance curve (t(0.5)) were calculated.


RESULTS
The patients had substantially faster t(0.5) (mean 23.9 (9.6) minutes) than normal values (>45 minutes). Thirty seven patients (35%) died during follow up (median 15 months). Univariate Cox regression analysis identified significant predictors of survival as age, forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), total lung capacity (TLC), % predicted TLC, carbon monoxide transfer factor (TLCO), % predicted TLCO, arterial oxygen tension (PaO(2)), oxygen saturation, t(0.5)F, and HRCT fibrosis score. Multiple stepwise Cox regression analysis identified t(0.5)F (p=0.03, hazard ratio 0.747, 95% CI 0.578 to 0.964), % predicted TLC (p=0.02, hazard ratio 0.976, 95% CI 0.956 to 0.995), % predicted TLCO (p=0.003, hazard ratio 0.960, 95% CI 0.935 to 0.986), and age (p=0.003, hazard ratio 1.062, 95% CI 1.021 to 1.104) as independent predictors of survival.


CONCLUSIONS
These data suggest that (99m)Tc-DTPA clearance t(0.5)F measurement may predict survival in patients with UIP pattern IPF.
Mogulkoc
N
N
North West Lung Research Centre, South Manchester University Hospitals, NHS Trust, UK. 1000046.1102@compuserve.com
Brutsche
M H
MH
Bishop
P W
PW
Murby
B
B
Greaves
M S
MS
Horrocks
A W
AW
Wilson
M
M
McCullough
C
C
Prescott
M
M
Egan
J J
JJ
D000368:Aged; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D005260:Female; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011658:Pulmonary Fibrosis / Q000378:metabolism*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D012044:Regression Analysis; D012129:Respiratory Function Tests; D016019:Survival Analysis; D016284:Technetium Tc 99m Pentetate / Q000493:pharmacokinetics*
D019275:Radiopharmaceuticals; D016284:Technetium Tc 99m Pentetate