1. Linking with Birth Certificate Data to Improve Patient Follow-up in Central Cancer Registries Daixin Yin, Janet Bates, Mark Allen, Lilia O’Conner California Cancer Registry Public Health Institute NAACCR 2008 Annual Conference

2. This presentation examines the linkage of registry data with maternal data from birth certificate as a way to improve follow-up. Need and challenge of patient follow-up Maternal data from birth certificate as a source for follow-up Linkage results & Discussion Linkage methods

3. The Need: Timely follow-up information on cancer patients are needed. 1. 1.To meet data quality standards (SEER, Acos CoC, and NAACCR certification) on patient follow-up Age < 20at least 90 percent but must not be below 80 percent 2. 2.To calculate population-based cancer survival rates 3. 3.To conduct population-based cancer survival studies

4. The challenge: Lifetime follow-up of cancer patients is an increasingly challenging task for central cancer registries. 1. 1.Improved survival for many cancers = increased load for patient follow-up 2. 2.The longer a registry has been in operation, and/or the larger the population = the larger its load for patient follow-up 3. 3.Active follow-up method -- very labor intensive and costly 4. 4.Passive follow-up method -- cost-effective, but some sub-groups (childhood or young adult cancer survivors) are not well-represented in commonly-used data sources.

5. Could maternal data from birth certificate files be used as a passive follow-up source? 1. 1.Is the data available to the central registry? Yes. Usually free or at minimal cost. 2. 2.Are appropriate linkage variables available in the file so that linkage is possible? Yes. California: SSN, first name, maiden name, date of birth, residence address, city, and zip code of the mother.

6. Could maternal data from birth certificate files be used as a passive follow-up source? (cont.) 3. 3.Will the central registry maintain the confidentiality of its files during the linkage? Yes. The registry can perform the linkage in house by obtaining electronic birth files. 4. 4.Will the source provide timely follow-up? Yes. In California, year 2005 birth certificate data file was ready by August 2006.

7. Linkage methods: A sequential matching algorithm 1. 1.Integrity® software was used 2. 2.A sequential matching algorithm = Records that did not match in one pass went on to a subsequent pass 3. 3.Pass 1 to pass 3 – deterministic method Variables have to match exactly between the two files. Pass 4 to pass 7 – probabilistic method Minor variations (such as Sandy vs. Sandi, or 214-15-5973 vs. 241-15-5973) were allowed.

8. Linkage process and results

9. Results: How many patients were matched and how many obtained updated date of follow-up? All matched patients All patients in the linkage Is Date of Birth of the child (from birth data) > Follow-up Date (in the registry)?

10. Results: Why only a small proportion of patients were matched in the linkage? 1.Based on total birth rate in California* (70.6 per 1000 women), there are less than 7.06% women who had given birth in the general population in a given time period. 2.Women who were diagnosed with cancer are likely to have a lower birth rate than women in the general population. # * Source: National Center for Health Statistics natality data, 2003-2005 average. # Nicholson HS, 1993, and Byrne J, 1987

11. Results: Why only a small proportion of matched patients get updated date of follow-up from birth data? Because the registry (CCR) has already used extensive data sources routinely to update patient follow-up information.  Death certificate data  SSA Epi  SSDI  NCOA (National Change of Address)  Cal Voter (Voter registration data)  DMV  OSHPD (Hospital discharge data)  NDI (National Death Index)  CMS

12. Discussion: Did the linkage capture more patients from any particular population sub-group?

13. Discussion: Did the linkage capture more patients from any particular population sub-group? (cont.) Note: Hispanic patients have a lower follow-up rate than non-Hispanic whites In California.

14. In summary, 1. 1.Birth certificate data could be used as a passive follow-up source. Usually readily available, free or at minimal cost. 2. 2.Linking with maternal data could effectively improve follow-up date, especially for younger patients, or Hispanic patients. 3. 3.For registries that currently use fewer follow-up data sources, the percentage of patients who obtain more current follow-up date could be much higher. For more details, please refer to:Linking with Birth Certificate Data to Improve Patient Follow-up in Central Cancer Registries. Journal of Registry Management 2008; 35 (3): 21-26.

15. Further steps: 1.Data items other than date of follow-up (such as birth place of mother, race/ethnicity of mother, years of education of mother), can be used to update demographic information for matched patients. Address variables from birth files can also be used to update patient contact info. 2.Paternal data from birth certificate could also be linked with registry data as another potential source of passive follow-up. Questions?