The more remote prognosis has always been a matter of
interest and speculation. It is said above that a patient " recovers
". But he is a marked man and, whether the illness has been short and sharp or long and
smouldering, whether there has been total effusion or a small one, whether
serial involvement of one pleural space after another has occurred with
recurrences of fever or not, patients who have been through an effusion of this
sort have a 25 per cent chance of developing clinical pulmonary tuberculosis
within 5 years. It was the inescapable fact, of the toll in tuberculous
morbidity following pleural effusion, which gradually compelled the adoption of
the view that all primary pleurisies are of tuberculous origin unless clearly
proved otherwise.
Much
laborious work has been put in at follow-up inquiries, but there are few series
of cases which are free from some sort of objection. It is important that a series should comprise
as large a number of patients as possible and that the number untraced should
be minimal. Strict criteria are necessary in diagnosis at the time of the
effusion (in order to eliminate cases of pulmonary tuberculosis of outspoken
type), and the follow-up examinations should be as comprehensive as
possible. The period of observation
should be at least 5 years.
The
accompanying table summarizes some of the more important facts to be obtained
from certain of the published follow-up inquiries. Each individual series
comprises more than 100 cases.
