Slow gait speed predicts poor prognosis in patients with IPF
medwireNews: Study findings suggest that slow gait speed is significantly associated with an increased risk of mortality and hospitalisation among patients with idiopathic pulmonary fibrosis (IPF).
The investigation included 130 patients with newly diagnosed IPF who attended outpatient respiratory clinics at a UK hospital between 2015 and 2016, 18% of whom died over 1 year of follow-up. Patients were aged an average of 72 years, and the average 4-metre gait speed (4MGS) was 0.91 m/s at baseline.
As reported in the European Respiratory Journal, the 46 patients categorised as having slow 4MGS (<0.8 m/s) had a significantly higher 1-year mortality rate than the 81 patients with preserved 4MGS (≥0.8 m/s), at 32% versus 11%.
These results translate into a significant 2.63-fold increased risk of mortality among patients with slow 4MGS after adjustment for factors including age, sex, smoking and forced vital capacity (FVC), say Claire Nolan (Royal Brompton and Harefield NHS Foundation Trust, UK) and co-investigators.
Similarly, gait speed measured as a continuous variable was significantly associated with mortality risk, with an adjusted hazard ratio (HR) of 0.03 for each 1.00 m/s increase in 4MGS.
And when gait speed was incorporated into a model together with age and FVC, the model including slow 4MGS had an accuracy of 81% for predicting mortality, whilst the model including 4MGS as a continuous variable had an accuracy of 79%.
These models “demonstrated better discrimination for predicting all-cause mortality than established composite prognostic indices”, write the researchers.
The team also found that rates of all-cause nonelective hospital admission were significantly higher among patients with slow compared with preserved 4MGS (57 vs 19%; adjusted HR=2.76), and the risk of hospitalisation decreased with every 1.00 m/s increase in 4MGS (adjusted HR=0.02).
Nolan and colleagues say that models including either slow 4MGS or gait speed measured as a continuous variable, together with diffusing capacity of the lung for carbon monoxide and number of chest infections in the previous year, “had good discrimination for hospitalisation”. These models correctly distinguished between patients who were and were not admitted to hospital on 79% and 78% of occasions, respectively.
In light of these findings, “[w]e propose that 4MGS may have value as a stratification tool of adverse outcomes in clinical trials”, say the study authors.
“It may also aid clinicians to monitor functional performance, identify patients at increased risk of poor prognosis and guide management strategies (e.g. frequency of clinical review and referral to other services)”, they add.
The researchers note, however, that their findings require validation in independent cohorts.
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