Practical implications of imposing a new world standard population

Area of Science:

• Epidemiology
• Biostatistics
• Cancer Research

Background:

• The World Health Organization (WHO) introduced a new world standard population for age-standardized rates.
• Current practice often uses the Segi (1960) standard population for cancer rate standardization.
• Evaluating the adequacy of different standard populations for relative risk estimation is crucial.

Purpose of the Study:

• To compare cancer rates standardized to the new WHO world standard population versus the Segi (1960) standard.
• To assess the adequacy of these standards as estimators of relative risk across diverse populations and over time.
• To determine if replacing the Segi standard with the WHO standard is necessary for cancer rate comparisons.

Main Methods:

• Calculated and compared incidence and mortality rates standardized to both WHO and Segi reference populations for various cancers.
• Compared standardized rate ratios with Mantel & Haenszel and maximum-likelihood estimators for approximating relative risk.
• Tested differences using a synthesis of relative risks, considering homogeneity of effects across age strata.

Main Results:

• No statistically significant differences were found between relative risk estimates derived from direct standardization and Mantel & Haenszel methods (p < 0.99).
• Similarly, no significant differences were observed when compared with maximum-likelihood techniques (p > 0.99).
• These findings held true regardless of whether the Segi or WHO world population was used as the standard.

Conclusions:

• Age-standardized rates using the Segi world standard population approximate relative risk as precisely as the WHO standard population.
• The Segi standard population is considered adequate for comparisons between cancer rates.
• Due to the precision and practical reasons, replacing the Segi standard population for cancer rate comparisons is deemed unnecessary.