In a cohort study, the standardized mortality ratio (SMR) for a group of coal miners compared to the general population is 1.8 (95% CI: 1.4-2.3). This means:

• A Coal miners have 1.8 times MORE deaths than expected in the general population
• B The mortality rate in coal miners is 80% of the general population
• C 18% of deaths in coal miners are attributable to occupational exposure
• D Coal miners have 80% excess mortality compared to the general population ✓

Explanation

SMR = (Observed deaths / Expected deaths) × 100. An SMR of 1.8 (or 180 when expressed ×100) means the observed deaths are 1.8 times the expected deaths based on the general population age-sex-specific rates — an 80% excess mortality (80% more deaths than expected). SMR > 1.0 indicates excess mortality; SMR < 1.0 indicates protective effect. The CI of 1.4-2.3 excludes 1.0, confirming statistical significance. SMR is used in indirect standardization where the standard population rates are applied to the study population's age-sex distribution.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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