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EFFECTS OF EMPLOYMENT ON HEART DISEASE
371
approximation. For this calculation it has been assumed that limited work in the
over-all picture is equivalent to employment during one half of the elapsed time.
On this basis a formula has been devised to indicate the proportion of working time
since heart disease was diagnosed. In this formula the number of years of full time
work and one half the number of years of limited work are added, and the sum is
divided by the number of years since heart disease was diagnosed. Thus, an indi
vidual whose heart disease had been known for 10 years and who had worked five
years full time and five years at limited work would be considered as having worked
75 per cent of the time.
5 + 2.5 10
0.75
Using this crude method, we calculated the proportion of working time in rela tion to functional classification and in relation to age. The results are given in tables 5 and 6. They can be summarized briefly by stating that except for those having a functional classification of "3" or worse and those in the age group of 55
Table 5.--Percentage of Time Worked Since the Discovery of Heart Disease of 580 Patients, By Functional Classification
Functional Classification at Discovery of
Heart Disease *
Patients Who Had Never Worked, Owing to
,------------- * Cardiac Other Reasons Reasons
f
Under 25%
Patients Who Had Worked Given Percentage of Time
25-49% 50-74% 75-99% 100%
Total
p & p t................................ :................ :.. 1........................................................................... 2 .............................................................
0 3 31
0 0 2 0 6 26 34 1 1 1 11 19 81 117 8 5 10 48 24 126 252
3 and worse...........................................
Cl
7 2 0 43 12 46 177
t Total........................................... ..
--
__ -- -- -- -- -- --
16 8 19 102 61 279 580
* The classification follows the 1940 Classification of the New York Heart Association.
I. Functional classification (degree of cardiac disability)-- Class 1. Ordinary physical activity does not cause discomfort. Class 2. Ordinary physical activity causes slight discomfort.
Class 3. Ordinary physical activity causes marked discomfort.
Class 4. Patient Is unable to carry on any physical activity without discomfort. II. Therapeutic classification (recommendations for physical activity)--
Class A. Physical activity need not be restricted. Class B. Ordinary physical activity need not be restricted, but patient should be advised, against
unusually severe or competitive efforts. Class C. Ordinary physical activity should be moderately restricted, and more strenuous habitual
efforts should be discontinued. Class D. Ordinary physical activity should be markedly restricted. Class E. Patient should be at complete rest, confined to bed or chair, t The abbreviation stands for possible and potential heart disease.
years and over, most of the patients in this series had worked most of the time since
their heart disease became known. Approximately two thirds of the class 1 and 2
patients, and a similar proportion of those under 35 years of age, were found to have
remained in full time unlimited employment for the entire period of known heart
disease.
Detailed analyses were made of the relationship between age, length of time the
patients had been followed in the clinic, changes in the functional and therapeutic
classification during this period, and past working experience. Statistical data on..
this material are too voluminous for presentation^ tyut a summary of the information
follows:1
'
In general, patients under 35 have been followed in the cardiac clinic for a long
period, many of them for more than 15. years. They have been working for the
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