Introduction Hyperventilation syndrome has a prevalence of 6–11% in primary care, and can be treated via breathing retraining. Breathing retraining reduces hyperventilation and improves symptoms. However, it is staffing intensive. Therefore, we examined which patient characteristics are associated with benefit from breathing retraining.

Method Retrospectively, we identified 201 consecutive patients referred to the breathing retraining service (February 2003 to June 2009) at a single site. Treatment efficacy was assessed by the treating physiotherapist according to resolution of symptoms. Success was defined as complete or near complete resolution of symptoms at the end of the breathing retraining period. Height, age, sex, smoking status, ethnicity, hyperventilation type (acute or chronic), restrictive/obstructive spirometry and known cardio/respiratory disease were also recorded. Patient characteristics were compared by treatment efficacy using χ² tests and t-tests, and logistic regression was used to identify which characteristics were independently associated with treatment efficacy.

Results The mean (SD) age was 50.9 (15.5) years. 38.3% were male and 31% had acute hyperventilation. 15.9% had obstructive and 10.5% had restrictive spirometry. 46.3% had known cardiovascular or respiratory disease. 61 patients overall benefited from breathing retraining. Current smokers were much less likely to benefit from breathing retraining compared to non-smokers (1 in 16.5 vs 1 in 2.4, p=<0.01). This association persisted after adjusting for the above patient characteristics. Ex-smokers had a similar probability of benefiting to that of non-smokers (1 in 3). Known cardio-respiratory disease was also independently associated with a lower odds of benefiting. The ORs for successful breathing retraining are shown for each predictor in the Abstract P189 Table 1. None of the remaining characteristics were associated with treatment efficacy.

Conclusion Our sample size was comparatively small as reflected in the wide CI, and the outcome measure was subjective. Nevertheless, smoking status is strongly associated with physiotherapist-assessed treatment efficacy following breathing retraining. Smokers, but not-ex-smokers are much less likely to benefit from breathing retraining. Therefore referral for smoking cessation rather than breathing retraining may be more appropriate in this patient group. It was not possible to assess long term benefit from this retrospective study.