DURATION. PRIVATE. PUBLIC. TOTAL
1 mo. to
3 mos. . .
1 yr. . . .
1 yr. to
2 yrs . . .
2 yr. to.
3 yrs ...
Total .
TI
We see from this table that the natural history of psoriasis is reckoned by years rather than by months or days. Thus, out of 414 cases in which reliable data were preserved, it is found that in 231, or 56 per 100, the éruption had existed for a period of over five years, and in four instance it is recorded that the éruption had been présent between 40 and 50 years before the patient came under treatment.
Gomparatively few cases were observed at or soon after the beginning of the disease, only 20 in whom it had lasted less than three months. It will be seen
Appendice
later that this is a fact of no little importance in connection with the proper treatment of the disease.
It would be interesting to know more deünitely the exact duration of the disease in those patients jwho hâve become free from the éruption and who hâve remained without any manifestations ; but unfortunately such statistics are extremely difficult to obtain in an office practice and among out-patients, who are seen only during the actual existence of the éruption, or who seek ad vice only as long as they may desire ; moreover, a large number of such cases are seen but once or twice, generally in consultation. Something more, however, can be learned of the obstinacy of the complaint by a considération of the length of time during which some of the patients were under observation, either for a continued existence of the éruption or for récurrences of the same. This is exhibited in the following table :
