When we turn from statistics to evidence of a safer kind there can be no question that not infrequently several cases of arthritis de formans occur in the same family, and although this is a less common occurrence than with gout and rheumatism, such examples are suffi ciently common to warrant the conclusion that arthritis deformaus is to some extent an hereditary disease. Even here we may be deceived and ascribe to the influence of heredity an association which is in reality due to several members of a family being alike exposed to the exciting causes of the malady.
As a typical example of such a family history I may quote the case of a poor woman who was under my care, who was a sufferer from typical arthritis deformaus, and who stated her father and mother both had enlarged joints. She was one of fifteen children, only six of whom lived to grow up, and her three brothers and two sisters were all said to suffer from enlargement of the joints such as she herself exhibited.
I have not found that such family histories are to be obtained more frequently iu cases in which the disease is developed at an unusually early period of life than in those in which it has a later onset; whereas those who suffer from gout at an early age nearly always have a strong hereditary tendency to that malady.
Such statistics as those above quoted appear to lend countenance to the idea which was formerly very prevalent that there exists an arthritic diathesis, a predisposition to articular disease, upon which gout, rheumatism, or arthritis deformaus is apt to become developed. It is difficult to reconcile such a view with the fact that gout and rheumatism, at any rate, are not merely diseases of the joints with visceral complications, but are systemic disorders of which arthritis is merely a prominent manifestation. Nevertheless it must be con fessed that the intricate way in which these various disorders are mixed up in certain families, and even occur iu succession in the same indivi dual, lends some countenance to the hypothesis of " arthritism." Another group of observers" insist that the tubercular diathesis is one of the most important of the conditions predisposing to arthritis deformaus, and maintain that a tubercular family history is extremely common among those who suffer from it. I believe that Dr. Fuller
was the first to advance this view. Tubercle contributes so largely to the general death-rate of the community that families in which that disease cannot be traced are perhaps rather in the minority, and in order to obtain any at all trustworthy statistical evidence upon this point, it would be necessary to compare the family histories of a series of patients with arthritis deformans with those of a series of patients not so afflicted. Such evidence would have more value than in the case of many other diseases, seeing that a death from consump tion in the family makes a deep impression, and the information afforded on the point is as a rule fairly reliable.
I cannot say that I have ever been struck by any special liability of members of tubercular families to arthritis deformans, nor am I prepared to go with those who assign to the tubercular diathesis any very large share in its causation.
TILe Ii acace of Sex.—In the multiple form of arthritis defor mans the influence of sex is strongly marked. Whereas gout is far commoner in men than in women and acute rheumatism falls with an approach to equality upon both, this disease attacks women far more commonly than men. Among the five hundred patients re ferred to above, there were no less than four hundred and eleven women and only eighty-nine men, and the inequality would have been still more conspicuous but for the fact that cases of the local ized type were included as well as those in which many joints were involved; such examples constituted a considerable proportion of the male This greater liability of the female sex is not con fined to any particular period of life, but is observed even in the rare cases in which the disease occurs in children. It is least con spictous in old age.
lnflue1ice of Aye.--The liability is greatest between the ages of forty and fifty-five, but no age enjoys immunity from attack. Cases occurring in early adult life are apt to assume a more acute form, and the disease usually spreads then with much greater rapidity, than in older patients in whom it tends to advance but slowly and fart passe with other senile changes. The curve and table which are here appended show the ages of incidence in the five hundred eases.