Survival in patients with cryptogenic fibrosing alveolitis: a population-based cohort study.
OBJECTIVE
To determine the median survival of patients with cryptogenic fibrosing alveolitis, in comparison to that expected of individuals of the same age and sex from the general population. To estimate the effect of survival bias incurred by studying both incident and prevalent cases. To identify factors associated with survival.


METHODS
Cohort study.


METHODS
Nine hospitals from the Trent Region of England.


METHODS
Two hundred forty-four cases of cryptogenic fibrosing alveolitis: 168 patients were alive on day 1 of the study (prevalent cases), and 76 patients had newly diagnosed conditions over a prospective 18-month period of patient recruitment (incident cases).


METHODS
Age, sex, date of diagnosis, lung function at presentation, and details of treatment prescribed were extracted from hospital clinical records. Data on lifetime smoking habits were collected by postal questionnaire. Vital status was established from the general practitioner. The expected survival of each case was extracted from the English life tables.


RESULTS
Median survival for incident cases was 2.9 years and for prevalent cases 9 years, compared to expected values of 10 and 13 years, respectively. Incident cases had significantly worse survival than prevalent cases, even after adjustment for the effects of age, sex, smoking history, lung function at presentation, and treatment (hazard ratio, 4.53 [95% confidence interval, 2.71 to 7.56]; p<0.001). Lower FVC at presentation and the use of corticosteroid treatment were both associated with worse survival.


CONCLUSIONS
The inclusion of prevalent cases leads to significant overestimation of the median survival for patients with cryptogenic fibrosing alveolitis. In newly diagnosed cases of cryptogenic fibrosing alveolitis, median survival is only 2.9 years, and expected life span is reduced by approximately 7 years.
Hubbard
R
R
University of Nottingham, Division of Respiratory Medicine, Queens Medical Centre, UK.
Johnston
I
I
Britton
J
J
D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000367:Age Factors; D000368:Aged; D015982:Bias; D015331:Cohort Studies; D016001:Confidence Intervals; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008017:Life Expectancy; D015993:Life Tables; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D015995:Prevalence; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011658:Pulmonary Fibrosis / Q000188:drug therapy / Q000453:epidemiology / Q000401:mortality* / Q000503:physiopathology; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology; D015996:Survival Rate; D014797:Vital Capacity / Q000502:physiology
D000305:Adrenal Cortex Hormones