How to Compute Delay Age-Adjusted Rates in Joinpoint

Overview

A delay age-adjusted rate is computed in a similar way to an age-adjusted rate.  The only difference is that the count is adjusted for reporting delays.  That adjustment is typically based on fields such as cancer site, registry, race, age, and diagnosis year.   For more information on delay adjustment please go here.

If Joinpoint is supplied with the appropriate information, it can compute delay adjusted rates and their associated standard error.   To have Joinpoint compute delay-adjusted rates, you must supply the following:

• All cohort-defining variables
• Independent Variable
• Adjustment Variable (this is typically an age variable)
• Count
• Delay Factor
  • This can be a primary delay factor or a composite delay factor.
  • The count is multiplied by the delay factor to adjust for the reporting delay. This factor is also used to compute the standard error.
  • The delay factor will be over 1.0 for the more recent years of diagnosis (those years affected by the reporting delay) and is 1.0 for older years of diagnosis (when there is no delay in reporting).
• Population
• Standard Population

 What is a Primary Delay Factor and a Composite Delay Factor

A primary delay factor is a factor that is produced from a statistical modeling process to account for reporting delay.  Primary factors are generally produced from the combination of several variables (e.g., race, age, diagnosis year, cancer site, registry, etc.).  If Joinpoint is provided with primary delay factors, then it will compute the delay rate and standard error identical to SEER*Stat.

A composite delay factor is a factor for any combination of variables (e.g., race, age, diagnosis year, cancer site, registry, etc.) produced as a weighted average of primary factors.  If Joinpoint is provided with composite delay factors, then it will compute delay rates, and standard errors close to SEER*Stat.  These usually match SEER*Stat within a few decimal places.

 Requirements When Having Joinpoint Compute Delay Age-Adjusted Rates

The following requirements will be applied to each cohort when delay age-adjusted rates are computed by Joinpoint:

• The data must be sorted using the following variable order:
• All cohort defining variables
• Independent variable
• Adjustment variable
• Count values must be greater than or equal to zero.
• Delay factors must be greater than or equal to 1.0 and less than or equal to 20.0.
• Population values must be greater than or equal to zero
• The count must not be greater than the associated population.
• Standard Populations values must be greater than zero.
• The Adjustment Variable must have the same categories (in the same order) for each By Variable/Independent Variable combination.

Below is an example of an input data file correctly structured for Joinpoint to compute delay age-adjusted rates.  The data file contains one by variable (sex:1 = Male, 2 = Female) and the independent variable is Year (values are 1992 thru 2022 inclusive). For each Sex/Year combination, there is a complete set of adjustment variable values (00 years to 90+ years). Please note that the standard population appears on every data record and the value corresponds to the associated age group.

Below is an example of how a delay age-adjusted rate is computed. The delay age-adjusted rate is 489.4 and is the sum of the interim values over all age groups.  The interim value in each row is equal to (Delay Crude Rate * Age Distribution of Std Pop). The Delay Crude Rate is the Delay Count / Population.