1995 OPEN FORUM Abstracts
A SUBJECTIVE SCORING TOOL FOR ASSESSING REVERSIBLE AIRWAYS OBSTRUCTION
M Snow RPFT, K Kandal RRT and R Fallat MD California Pacific Medical Center, San Francisco, California
BACKGROUND: Comparisons of methods for detecting Reversible Airways Obstruction (RAO) are commonly made against spirometric measurements of FEV1 and FVC. Airway Resistance (Raw, SRaw) is generally more sensitive for detecting RAO but without an independent quantification, specificity cannot be assessed. Since the goal of bronchodilator therapy is to effect a change in respiratory status whichcan be perceived by the patient, we developed a tool for quantifying a patients' subjective response.
Methods: A Borg-type scale was developed to permit a patient to select a description of respiratory status defining baseline condition as well as response to medication. The scale provides a seven point description of baseline condition ranging from much worse to much better than average and medication response ranging from worse to excellent response. The tool was evaluated on 438 consecutive patients with complete PFTs before and after administration of albuterol MDI (3 puffs). Each patient subjectively scored baseline status as well as response to medication and after testing rescored baseline status to determine a change post testing. Stepwise linear regression and Chi-Square analysis versus subjective scoring was used to assess sensitivity/specificity and correlation between subjective response versus difference between starting/ending baseline scores.
ATS Response Subj Score >=DefiniteSubj Score<Definite Total
FEV1 Yes (>0.2L & 12%) 82 32114
FEV1 No ( < 0.2L OR 12%) 147177 324
Total 229209 438
r2=0.06 Sensitivity 36% Specificity 85%
SRaw CriteriaSubj Score >=DefiniteSubj Score<Definite Total
SRaw Yes (>25% & 1.2)18371254
SRaw No ( < 25% OR 1.2)46 138 184
Total 229209 438
r2=0.36 Sensitivity 80% Specificity 66%
Subjective (End - Start)
Response to Med r2=0.66
Since airway resistance directly assesses the mode of action for bronchodilator, sensitivity and specificity should be high for patient perception of response. Results strongly correlate with subjective score. The high correlation between medication response and change during testing suggests internal validity.
Conclusions: 1. Patient Subjective Scoring correlates strongly with objective response indices. 2. Baseline Scoring provides a reproducible criteria for trending patients for followups. 3. Comparisons of change from baseline scoring to end of test scoring correlates strongly with subjective response scoring.