Correlation of nasal symptoms with objective findings and surgical outcome measurement

Thesis submitted for the degree of Master of Surgery, University of London, 1993.
Published (excluding Chapter 9) 1996.
Recompiled HTML format June 2007
© 1993 – 2014 JW Fairley

Mr James W Fairley BSc MBBS FRCS MS
Consultant ENT Surgeon

Chapter 6
The relationship between symptom scores on a specially designed questionnaire and corresponding objective measurements: Nasal inspiratory peak flow and subjective sensation of nasal obstruction

Thesis Contents

Summary

The relationship between subjective and objective nasal obstruction was studied using a Youlten Nasal Inspiratory Peak Flow meter in 133 patients attending a Nasal Research Clinic.

There were 56 men and 77 women.

Mean NIPF was 135 litres per minute in men, and 118 litres per minute in women (p = 0.023, unpaired 2 tailed t-test).

A highly significant inverse relationship (R = minus 0.264, Kendall’s Tau C = minus 0.22854, p = 0.0007) was demonstrated between the objective measurement of nasal inspiratory peak flow rate and the subjective degree of nasal obstruction on the 4-point ordinal scale used in the symptom questionnaire.

This relationship was valid in women when analyzed separately, but not in men.

The value of the relationship in predicting the degree of subjective nasal obstruction from the objective measurement is limited; overall it reduces error in prediction by 7.5%, in women 14% and nil in men (Goodman and Kruskall’s Lambda).

Therefore it is not reasonable to use nasal inspiratory peak flow as an objective equivalent of subjective nasal obstruction, particularly in men. The relationship accounts for only around 7% of the variation, and I have shown previously (Chapter 2) that the method itself has a coefficient of variation of 8%.

It would not be reasonable to say to an individual patient “Your test shows the nose is not blocked”.

Nor is it reasonable to use NIPF as a primary measure of outcome in nasal surgery, although it could be used as a secondary measure of technical success of treatment, bearing in mind its limited value in predicting subjective nasal obstruction.

Outcome measurement in surgery for nasal obstruction must therefore be based primarily on the subjective opinion of the patient.