The report by Haddad and Risk [ l ] of isoprinosine treatment in subacute sclerosing panencephalitis (SSPE) raises a number of questions.
The claim of a controlled study, made in the title, is not borne out in the text, where 18 treated cases are compared with what appear to be 96 unmatched, historical controls.
The 18 treated patients cannot be considered to have had adequate trials of the drug: the mean duration of drug treatment was only 12 weeks, with a range of 2 to 27 weeks. The criteria for discontinuation of therapy are not given. In the absence of evidence of virological cure, we have continued the drug indefinitely-for as long as eight years in our longest survivor. Remissions, when they have occurred, have not been associated with onset of isoprinosine therapy, but have usually become evident after 3 to 12 months of treatment [2].
Haddad and Risk suggest that a chronic remitting course of SSPE may be more likely with later age of onset. However, their data fail to support this: in 10 rapidly fatal cases the mean age of onset was 10.6 years & 1.1 SEM, while the 8 patients who survived four or more years had a mean age at onset of 8.3 years & 1.0 SEM. Finally, the 18 isoprinosine-treated patients showed a different four-year survival from the 96 control cases of SSPE. The four-year survival in these controls, reported by Haddad et al in 1977, was about lo%, while the four-year survival among the 18 isoprinosine-treated patients was 44% (8 out of 18). Is this due to case selection? to a changing pattern of SSPE in Lebanon? to isoprinosine? Answers to these questions await a true controlled study, which could be carried out in the Near East, where this disease continues to be relatively common.