84 Milton Landowne 



age. In over one-third of all 78 subjects, the toe temperature 

 did not exceed the group mean of 30-7° C. Among the 40 

 subjects who were older than the mean age of 58, two-thirds 

 did not attain this temperature. Nine of the 11 subjects who 

 showed minimal clinical evidence of functional impairment 

 had responses to less than mean values, but there were 18 

 subjects clinically graded as class 1 whose responses were no 

 better. The response of 8 patients with manifest and advanced 

 disease of classes 3 and 4 have been added. In none of these 

 did the toe temperature exceed 30° C. However, they did as 

 well as 10 of the class 1 subjects in the same age range. This 

 might suggest that the test procedure lacks sensitivity or 

 selectivity. It may alternatively indicate that the functional 

 capacity of subjects and patients was about equally limited. 

 In the patients with manifest disease, symptoms and signs 

 had developed, while in the subjects who were not patients, 

 these complications of a latent disorder had not occurred. 

 Although useful, a single test of this kind cannot be considered 

 to establish a diagnosis without other corroborative evidence. 

 To be a good diagnostic procedure, a single test should provide 

 a small number of false positives and false negatives, but as 

 long as the incidence and distribution of the cases of disease 

 are not known with certainty, we cannot determine the 

 accuracy of detection by any proposed index; this includes 

 our own quasi-specific measurements. 



Somewhat more may be ventured in the way of interpreting 

 agewise changes in studies which deal with more specific 

 measurements, particularly if these are combined with other 

 equally or less specific measures in the same individual, or in 

 similar groups. This may be illustrated by the cardiac output 

 studies which we have made (Brandfonbrener, Landowne and 

 Shock, 1955). It might have been expected that we should 

 find cardiac output to decrease with age. Earlier work sug- 

 gested it. It had also been demonstrated, or indicated to be 

 likely, that regional increases in the renal, cerebral and ex- 

 tremity vascular resistance occurred with age. This would lead 

 to an increase in total resistance of the greater circulation, a 



