National Center for Health Statistics DCC CENTERS FOR DISEASE CONTROL AND PREVENTION Measuring Injury Using the National Health Interview Survey Margaret Warner, PhD Lois A. Fingerhut, MA Pat Barnes, MA Margaret Warner, PhD Lois A. Fingerhut, MA Pat Barnes, MA

Location of injury and poisoning data Injury Episode file Injury Verbatim file Poison Episode file Person file Injury Episode file Injury Verbatim file Poison Episode file Person file

Injury episode file For each person: Up to 4 injury episodes For each episode: Up to 4 ICD-9-CM diagnosis codes Up to 3 ICD-9-CM external cause codes For each person: Up to 4 injury episodes For each episode: Up to 4 ICD-9-CM diagnosis codes Up to 3 ICD-9-CM external cause codes

Available data in the Injury Episode file External cause (ICD-9-CM) Injury diagnoses (ICD-9-CM) Place of occurrence Activity Resulting limitations Detail on certain causes (e.g. mv crashes, falls) External cause (ICD-9-CM) Injury diagnoses (ICD-9-CM) Place of occurrence Activity Resulting limitations Detail on certain causes (e.g. mv crashes, falls)

ICD-9-CM diagnosis codes and E-codes are based on information supplied by respondents, not medically trained personnel. Injury episode file

Poisoning episode file Contains no ICD-9-CM codes or E-codes Contains 47 episodes coded as “Allergic/adverse reaction to medical or other substance” or “Something else – not poisoning” Contains no ICD-9-CM codes or E-codes Contains 47 episodes coded as “Allergic/adverse reaction to medical or other substance” or “Something else – not poisoning”

Available data in the Poisoning Episode file Cause of poisoning Call to poison control center Cause of poisoning Call to poison control center

Available data in both injury and poisoning files Date of episode Hospitalization Days out of school Days out of work Time elapsed between episode and interview Date of episode Hospitalization Days out of school Days out of work Time elapsed between episode and interview

Injury section–Person file Contains summary information about injury and poisoning episodes Annual estimates can only be made on variables INJCT and POICT Contains summary information about injury and poisoning episodes Annual estimates can only be made on variables INJCT and POICT

How do I put the data together?

Injury and poisoning episode, and injury verbatim files Contain only injury or poisoning information and unique identifiers Must be linked to the person file to obtain sociodemographic variables, design variables, etc. Contain only injury or poisoning information and unique identifiers Must be linked to the person file to obtain sociodemographic variables, design variables, etc.

Episode and person based files Episode based: A person will appear in these files as many times as he/she has a unique episodes Person based: A person will appear in this file only once Episode based: A person will appear in these files as many times as he/she has a unique episodes Person based: A person will appear in this file only once

Concatenating injury and poisoning episode files InjuryPoisoning + + = Missing data, questions not found in both files Injury Poisoning

Merging injury/poisoning episode file and person file + + Person Injury Poisoning = Missing data, questions not found in both files

Merged injury/poisoning episode file and person file Injury Poisoning Person = Missing data, questions not found in both files

Episodes and Conditions Episode = Event that caused the condition (e.g. fall down stairs) Conditions = physical harm resulting from the injury episode (e.g. broken leg, bruised arm) Episode = Event that caused the condition (e.g. fall down stairs) Conditions = physical harm resulting from the injury episode (e.g. broken leg, bruised arm)

Creating condition files Injury ICD9_1 ICD9_2 ICD9_3 ICD9_4 Injury Episode with ICD9_1 ICD9_2 ICD9_3 ICD9_4

Creating condition files Poisoning Poisoning episode Poisoning condition =

Concatenating injury and poisoning condition files Poisoning + + Injury conditions Poisoning conditions = Missing data, questions not found in both files

What Can I Do With the Data?

Handout Using SAS to manipulate the injury and poisoning data Example SAS programs for concatenating and merging the files Using SAS to manipulate the injury and poisoning data Example SAS programs for concatenating and merging the files

Analyzing the injury and poisoning data Estimates of frequency Percent distributions Rates Standard errors Estimates of frequency Percent distributions Rates Standard errors

Calculating annual estimates Annual est = (variable)(4)(WTFA) Annual estimates of episodes and conditions can be calculated. Annual estimates of the number of persons injured cannot be calculated due to the 3 month reference period. Annual est = (variable)(4)(WTFA) Annual estimates of episodes and conditions can be calculated. Annual estimates of the number of persons injured cannot be calculated due to the 3 month reference period.

Standard Errors (SE) SE of the injury/poisoning rate for males and females SE of the injury/poisoning rate for specified racial groups SE of the injury/poisoning rate for males and females SE of the injury/poisoning rate for specified racial groups

Estimates of frequency Examples Number of episodes resulting from specific causes Number of injury/poisoning episodes by sex Number of injury/poisoning episodes by mechanism Number of episodes resulting from specific causes Number of injury/poisoning episodes by sex Number of injury/poisoning episodes by mechanism

Results

Rates Examples Annual injury/poisoning rates for males and females Annual injury/poisoning rates by mechanism Annual rate of falls for females over 65 years of age Annual injury/poisoning rates for males and females Annual injury/poisoning rates by mechanism Annual rate of falls for females over 65 years of age

Injury and poisoning episode rates Age in years Episodes per 1,000 population 95% CI

Age adjusted injury episode rates by mechanism of injury Episodes per 1,000 persons

Age adjusted condition rates by type of injury, 1997

Percentages Examples Percent of episodes resulting from specific causes Percent of poisoning episodes in which a poison control center was called Percent of injury episodes that occurred in the home Percent of episodes resulting from specific causes Percent of poisoning episodes in which a poison control center was called Percent of injury episodes that occurred in the home

Percent of injury episodes by place of injury, 1997 Percent of episodes Persons could indicate up to two places per episode.

Work-related injuries Injury episode file: Activity at the time of injury= Working at a paid job Sample person file: Occupation and industry Injury episode file: Activity at the time of injury= Working at a paid job Sample person file: Occupation and industry

Percent of injury episodes by activity, 1997 Percent of episodes Persons could indicate up to two places per episode.

Injury verbatim file Responses recorded by the interviewer: How the injury occurred Body part injured Nature of injury Text file linkable to other files Responses recorded by the interviewer: How the injury occurred Body part injured Nature of injury Text file linkable to other files

Available data in injury verbatim How the injury occurred (up to 336 characters) Up to 4 body parts injured (up to 34 characters each) Up to 4 nature of injuries (up to 44 characters each) How the injury occurred (up to 336 characters) Up to 4 body parts injured (up to 34 characters each) Up to 4 nature of injuries (up to 44 characters each)

Injury verbatim file Edited only for confidentiality Grammatical and/or spelling errors were not corrected Edited only for confidentiality Grammatical and/or spelling errors were not corrected

Uses of injury verbatim NCHS used to code ICD-9-CM diagnoses and external causes Code according to other classification schemes (e.g. BLS, ICECI, etc) Text search for words of interest In-depth analysis of ICD-9-CM categories NCHS used to code ICD-9-CM diagnoses and external causes Code according to other classification schemes (e.g. BLS, ICECI, etc) Text search for words of interest In-depth analysis of ICD-9-CM categories

Check sample size Analysts should be cautioned against making estimates based on small numbers of observations.

Verbatim text Example Cause of injury:. Part of body: Type of injury: Cause of injury:. Part of body: Type of injury: “While, fell on thumb.” “Right thumb” “Broken”

Examples of verbatim Machinery related injuries (E919) “ He was at home working on his table saw and accidentally ran his left thumb through the machine lengthwise.” (table saw, n=8) “Forklift extension came loose dropping on right foot at work” (forklift, n=3) “ He was at home working on his table saw and accidentally ran his left thumb through the machine lengthwise.” (table saw, n=8) “Forklift extension came loose dropping on right foot at work” (forklift, n=3)

Contact for questions related to injury data or injury classification issues: