Hospital separations selection of records for injury surveillance

1. Hospital separations selection of records for injury surveillance Susan G. Mackenzie Public Health Agency of Canada Presented at ICE meeting in Cuernavaca June 2005

2. Selection of hospital separation records for analysis of external causes • What differences are there between (and within) countries? • Is there a generally preferred, or most common, approach?

3. Compare results of Canadian and US approaches using the same data set • Data set • All acute care separations from the province of Manitoba for 2000-01, excluding newborns and records with serious errors. • N=126,217 • Select all records where • The tabulating diagnosis is an injury (in chapter 17 of ICD-9) or • There is an external cause on the record • N=14,772

4. External cause on record Present Not present 8,254 (56%) 2,019 (14%) 17- Injury & poisoning ICD-9 Diagnosischapter 4,499 (30%) 0 Other 14,772

5. Exclude invalid diagnoses (chapter 17) and external causes • Invalid diagnoses – only in the US • Complications of care, adverse effects, allergic and anaphylactic reactions, others • Injury Surveillance Workgroup. Consensus recommendations for using hospital discharge data for injury surveillance. Marietta (GA): State and Territorial Injury Prevention Directors Association; 2003. • Invalid external causes – in Canada and the US • Adverse effects • Centers for Disease Control and Prevention. Recommended framework for presenting injury mortality data . MMWR 1997;46 (No. RR-14)

6. External cause on record Present Not present Valid Invalid Valid 7,785 7,785 129 129 17- Injury & poisoning None has a valid injury diagnosis Injury diagnosis 110 230 Invalid ICD-9 Diagnosischapter 8,254 8,254 2,019 2,019 Other 4,499 0 14,772

7. External cause on record Present Not present Valid Invalid Valid 7,785 7,785 129 129 17- Injury & poisoning None has a valid injury diagnosis Injury diagnosis 110 230 Invalid ICD-9 Diagnosis chapter 8,254 8,254 2,019 2,019 Valid Invalid 1-16 2,050 1,560 Diagnosis chapter Other 804 85 V-code 4,499 0 14,772

8. External cause on record Present Not present Valid Invalid Valid 7,785 7,785 129 129 17- Injury & poisoning US CA None has a valid injury diagnosis Injury diagnosis Invalid 110 230 CA ICD-9Diagnosischapter 8,254 8,254 2,019 2,019 Valid Invalid Total records retained from Manitoba 2000-01 hospital separation data CA approach 10,749 US approach 7,785 1-16 2,050 1,560 Diagnosischapter Other CA 804 85 V-code CA 4,499 0 14,772

9. Distribution of selected external cause groups using US and CA approaches data from Manitoba 2000-01

10. Most frequent groups of records kept only with the Canadian approach N=2,964

11. Summary • US selection based on • Valid injury diagnoses and valid external causes • Canadian selection based on • Valid external causes • Canadian approach yields more records • There are quite large differences in the rates for some external cause groups • Other countries?

12. Canadian Institute for Health Information Acute care No serious errors Adverse effects excluded Newborns included Other exclusions Poisoning, choking, late effects, travel & motion, hunger, thirst, exposure, neglect Public Health Agency of Canada Same Same Same Newborns excluded None Two approaches used in Canada

13. Compare overall results of the two Canadian approaches