Among asbestos cement workers, 48 deaths from respiratory cancer were observed during the study period, whereas only 24 such deaths were expected based on age and sex specific rates of the national population. The Standardized Mortality Ratio (SMR) and its correct interpretation are:
- A SMR 50, indicating half the expected mortality
- B SMR 24, indicating mortality equal to the general population
- C SMR 200, indicating a twofold excess mortality compared with the general population ✓
- D SMR 72, indicating combined observed plus expected burden
Correct answer: C. SMR 200, indicating a twofold excess mortality compared with the general population
Explanation
SMR equals observed deaths divided by expected deaths, multiplied by 100: 48 divided by 24 times 100 gives 200. An SMR above 100 means the study group experiences more deaths than would be expected if it had the same age and sex specific rates as the reference population. Option A comes from inverting the ratio, option B confuses the expected count with the index itself, and option D simply adds the two figures. SMR allows comparison of populations with different age structures.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.