Background - Primary spontaneous pneumothorax (PSP) is a common clinic
al problem and its incidence is thought to be increasing. The risk of
recurrence is high and various studies quote rates of 20-60%. Factors
which may or may not predispose to recurrence have not yet been establ
ished. Methods - In a study period of four years 291 cases with a diag
nosis of pneumothorax were reviewed; 153 patients with PSP were includ
ed in the study. Their risk of recurrence was analysed with particular
reference to the following variables: age, sex, height and body mass
index (BIMI) of the patient, the initial size of pneumothorax, the smo
king status of the patient, and the primary form of treatment employed
. Univariate analysis was carried out by chi(2) testing and multivaria
te analysis was calculated by a logistic regression model. Results - A
retrospective study of 275 episodes of PSP in 153 patients over a fou
r year period confirmed a high incidence of recurrence (54.2%). PSP wa
s twice as common in men as in women, though women were significantly
more likely to develop a recurrence (chi(2)=7.58, df=1, p<0.01). Male
height was the second most important factor, and smoking cessation the
only other variable which significantly influenced the risk of recurr
ence. Conclusions - Analysis of several potential risk factors reveale
d that recurrence was not related to the BIMI of the patient, the init
ial treatment of the pneumothorax, nor to its size. Recurrence was mor
e common in taller men and in women. Smoking cessation appeared to red
uce the risk of recurrence. These findings are discussed in the contex
t of the possible aetiology of spontaneous pneumothorax, recurrences,
and the management thereof.