Is physician-diagnosed allergic rhinitis a risk factor for the development of asthma?
BACKGROUND
There is strong evidence that there is a relationship between allergic rhinitis (AR) and asthma, but it is unclear whether there is a causal relation between AR and asthma. The aim of this study was to assess prospectively whether AR is a risk factor for the diagnosis of asthma in a large primary care population.


METHODS
We performed a historic cohort study of life-time morbidity that had been recorded prospectively since 1967 in four general practices. Two groups of subjects were selected: (i) patients with diagnosis of AR, (ii) a control group matched using propensity scores. We assessed the risk of physician-diagnosed asthma in patients with physician-diagnosed AR compared to subjects without a diagnosis of AR (controls).


RESULTS
The study population consisted of 6491 subjects (n = 2081 patients with AR). Average study follow-up was 8.4 years. In patients with AR, the frequency of newly diagnosed asthma was 7.6% (n = 158) compared to 1.6% (n = 70) in controls (P < 0.001). After adjusting the effect of AR on asthma diagnosis for registration time, age, gender, eczema and socioeconomic status, having AR was a statistically significant risk factor for asthma (hazard ratio: 4.86, P < 0.001, 95% confidence interval: 3.50-6.73, controls as reference).


CONCLUSIONS
A diagnosis of AR was an independent risk factor for asthma in our primary care study population. Having physician-diagnosed AR increased the risk almost fivefold for a future asthma diagnosis.
van den Nieuwenhof
L
L
Department of Primary and Community Care, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands. L.vandennieuwenhof@elg.umcn.nl
Schermer
T
T
Bosch
Y
Y
Bousquet
J
J
Heijdra
Y
Y
Bor
H
H
van den Bosch
W
W
van Weel
C
C
D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology*; D015331:Cohort Studies; D005194:Family Practice; D005260:Female; D006801:Humans; D057216:Propensity Score; D012221:Rhinitis, Allergic, Perennial / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology; D006255:Rhinitis, Allergic, Seasonal / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology; D012307:Risk Factors; D055815:Young Adult