Back pain, ventilatory function, chest symptoms, and smoking.

: Tests of ventilatory function were made and a history of previous back pain was obtained from 909 volunteers (592 men and 317 women). One year later, using postal questionnaires, they were asked about their experience of back pain in the ensuing 12 months and about smoking habits, breathlessness, coughing, and the bringing up of phlegm. From the frequency of their experience of back pain, the population was divided into "nonbacks," "mild backs," and "chronic backs." From their answers to the MRC Questionnaire on respiratory symptoms they were divided first into good, mild, and bad with regard to chest symptoms; and also into smokers, exsmokers, and nonsmokers. Ventilatory function tests were reduced in both smokers and "bad chests" and chest symptoms were significantly worse in smokers. Women with back pain were more likely to be smokers, but men with back pain were not. Chest symptoms were significantly worse in "chronic backs," whether men or women. The results suggest that previous reports of a relation between smoking and back pain arose incidentally from the associations between (a) chest and back symptoms and (b) chest symptoms and smoking.