Purpose: To investigate the impact of changes in diagnostic criteria and technology on the rates of occurrence of pulmonary diseases during each of four different calendar years: 1921, 1941, 1961, and 1982.
Patients and methods: The medical records were obtained for all patients discharged from Yale-New Haven Hospital during 1921, 1941, 1961, and 1982 with a diagnosis of either pulmonary tuberculosis or primary lung cancer. Each patient's entire clinical course was then thoroughly reviewed, including all available data obtained in the six-month intervals before and after the patient's hospitalization. Critical diagnostic information obtained during life at any time during this one-year period was acceptable as evidence for the diagnosis.
Results: According to modern diagnostic criteria, the existing evidence of pulmonary tuberculosis or primary lung cancer often did not justify those diagnoses in patients hospitalized during each of the four survey years. The proportions of justified diagnoses showed a consistent increase over time: 16%, 42%, 53%, and 86%, respectively, for tuberculosis, and 0%, 54%, 93%, and 93%, respectively, for lung cancer.
Conclusion: The results suggest that some of the statistical changes in occurrence rates for these two pulmonary diseases may be due to temporal improvements in diagnostic precision, not just to environmental changes or therapeutic advances.