# Presentation: 430440

## Improvements to the Collection of Injury and Poisoning Data in the National Health Interview Survey

**Patricia Barnes, M.A.**
**Margaret Warner, Ph.D.**
**Lois Fingerhut, M.A.**
**Melissa Heinen, M.P.H.**
**Montreal 2002**

**Centers for Disease Control and Prevention**
**National Center for Health Statistics**

**Notes:**
Hello. I am going to talk about the methods of collection of injury and poisoning data from the National Health Interview Survey.  I am Margaret Warner and am presenting for Pat Barnes who could not be here today.

## National Health Interview Survey

** ****Face-to-face household survey **
** ****Nationally representative sample of civilian, non-institutionalized US population **
** ****Sample yields data on approx. 100,000 persons per year**

## Timeline

** ****1957-96****	****Imbedded in questionnaire**
** ****1997-99****	****Section on injury & poisoning **
** ****2000-03 ****	****Combined inj & poi questions**
** ****2004      ****	****“Unpacked” screen question**

**Notes:**
This timeline summarizes key years in which changes to the survey were made.  And the talk is organized around it. I am going to go through major changes to the survey and hope that our experience will both inform those of you designing surveys and help analysts understand our survey.  From 1957-96, data on injuries and poisonings questions were essentially imbedded in the survey. That is, data on health related conditions were captured throughout the questionnaire and then all were ICD coded.  Injuries were defined as conditions coded between ICD-9CM codes 800-999.  

In an effort to increase the level of detail available on injury and poisoning episodes and to enable the user to make more reliable annual estimates, beginning in 1997, the NHIS completely changed the way it collected injury and poisoning data.  Questions specifically designed for injuries and poisonings were added and became a section of the questionnaire.  

Some questions in the section were asked when the person was injured or poisoned, but some were asked only of people injured and some only of people poisoned.  For 2000 survey, these two were combined into a common set of questions for both injury and poisonings.

In 2004 we have proposed changes again to the survey and specifically to the screener questions – and I’ll get back to this shortly.

I also want to note here that one of the things that makes the NHIS great is that it is a national survey - and one of the things that make it frustrating is that it is a huge survey that goes through layers of people designing, administering and editing and finally analyzing the data.   For instance, NCHS designs the survey and census actually programs and administers it and returns the data to NCHS who then edits and analyses it.  This makes things change rather slowly – which is why we talking about changing 2004 in 2002.

## Changes from the 1995 Survey to the 1997 Survey

** ****Placement, phrasing and ****	****number of questions**

-  **Recall period**

-  **Severity threshold**

**Notes:**
So now, I am going to go through each of these points of change in greater detail and tell you the results from the years.  

1) Beginning in 1997, questions asking specifically about injury episodes and poisoning episodes were added to the family core section of the NHIS.  In other words, the placement, phasing and number of questions changed.
2) The recall period was increased from two weeks in 1995 to three months in 1997.
3) The severity threshold was changed from events resulting in at least a half day of restricted activity and/or medical attendance in 1995 to only events resulting in medical advice or treatment in 1997.

The questions were developed through a long (as in multiple years), arduous process, they were tested in the our survey laboratory at NCHS, and were also field tested.   You can read more about this in a Series report  that Lois Fingerhut, Pat and myself wrote.  It is available at the NCHS website – I can give you more details if you need after the session.

## Data issues: 1997-1999

** ****Some questions not common to ****	****both injuries and poisonings**
** ****Injuries recorded as poisonings ****	****and poisonings recorded as ****	****injuries**
** ****High proportion in *****Other***** **
**  ****No question on treatment location**

**Notes:**
After analyzing the data from the 1997 survey, a number of issues were noted. 			
There were some questions that were not common between the injury and poisoning section 
2) In addition, respondents sometime answered that they had a poisonings when we would define it as an injury and vice versa.
3) Some response categories needed to be fixed... for example, some had 20% of responses as other
4) Finally we added a question on treatment location because there was interest from the users.
In order to get the changes into the 2000 - we were forced to make changes without testing.

## Changes: 1997-99 to 2000 Survey

** ****Combined injury and poisoning ****	****questions**

** ****Added a question about medical ****	****advice or treatment**

** ****Revised categories for several ****	****questions**

**Notes:**
So the changes from 1999 to 2000 survey include:

1) Now asking the same questions about both injury and poisoning episodes

2) Adding a question that ask the respondent where the injured or poisoned person received medical advice or treatment

3) Revising some of the categories of pre-existing questions.

## Screener question:1997-99 and 2000-present

**1997-99:** DURING THE PAST THREE MONTHS, that is since {91 days before today date}, {were/was} {you/anyone in the family} **injured** seriously enough that {you/they} got medical advice or treatment?
- DURING THE PAST THREE ... **poisoned** seriously enough that you ...?

**2000:** DURING THE PAST THREE MONTHS, that is since {91 days before today date}, {were/was} {you/anyone in the family} **injured or poisoned** seriously enough that {you/they} got medical advice or treatment?

**Notes:**
We combined the questions by adding “injury or poisoning” to many of the questions.  This is the screen questions for 1997-99 and for 2000 to the present.  This question is the one that “feeds” everyone who is injury or poisoned into the follow-on questions.

## Injury and poisoning

**Notes:**
This chart shows the annual number of injury and poisoning by year from 1997-2000.  And it shows the number of injuries dropped by 15% between 1999 and 2000.  You can also see a steady decrease in the years before.  

We actually saw the decline in the unweighted numbers when we got the data back from census in mid-July 2000.  We could not be sure if this was an issue with the weights or with the observations.   But is was at this point that we noticed a problem with a question

## Fixed Question Wording 

**2000:** How many different times in the PAST 3 MONTHS did {you/subject’s name} **seek medical advice** because {you/subject’s name} were injured or poisoned?

**1997-99:** How many different times in the PAST 3 MONTHS {were/was} {you/subject’s name} **injured seriously enough to seek medical advice or treatment?**

**Notes:**
This question follows the screen question I just described and is supposed to ask how many times the person was injured or poisoned.  In 2000, there was an error somewhere in the chain and the question was mistakenly worded how many times did you seek medical advice because you were injured or poisoned.
We tried to get it fixed as soon as we realized what had happened -- but were unable to get the correction into the field until 2001.   It was changed back to how many times the person was injured rather than how many times the person sought medical advice or treatment for an injury or poisoning. 

Preliminary data for 2001 show that it is similar to 2000.  Which makes sense since the mistaken question only applies to people with more than one injury which is very few – so although it may have been confusing – it wasn’t the answer to why the number of injuries and poisonings recorded dropped.
And unfortunately we did not have an easy answer.  The other problems were not as easily corrected. 

## Finding Solutions to the Other Problems

-   Analyzed data
-  Held a teleconference with the  	interviewers in the field

-  Sent the injury and poisoning section 	through the Questionnaire Design 	Research Lab

**Notes:**
In an attempt to correct the other problems we had discovered we decided to:
Analyzed the data
Hold a teleconference with the field representatives who administer the survey
Send the injury and poisoning section through the questionnaire design research lab at NCHS

We looked at age, sex, race, and cause and injury diagnosis and it did not appear and the decrease did not appear to be for any particular subgroup.

Talking with the field representatives gave us some insight into how respondents were reacting to the and possibly interpreting the quesitons. The interviewers also told us what they felt were problems with the injury and poisoning questions.

Testing in the questionnaire design research lab involved recruiting people who had been injured or poisoned, asking them the injury and poisoning questions, and then asking them questions about the questions.  From this testing, we learned how people are interpreting the questions and what about the questions they find confusing.  During this process, the questions are refined based on the information obtained from the respondents and then the questions are tested again.

## Unpacking the question

**2000-03: **DURING THE PAST THREE MONTHS, that is since {91 days before today date}, {were/was} {you/anyone in the family} **injured** or **poisoned** seriously enough that {you/they} got **medical advice or treatment**?

**Three questions in one:**
**Were you injured?**
**Were you poisoned?**
**Did you seek medical advice?**

**Notes:**
Both discussions with the interviewers and the cognitive testing suggested that our screen question was really three questions packed into one – and that perhaps people were not hearing the injury part of the question.  So we are proposing for 2004 that the question be “unpacked”

## Proposed for 2004

- During the past three months, that is since {January 2}, did you have an** ****injury where any part of your body was hurt, for example, with a broken bone, sprain, burn, wound, bruise, or animal or insect bite****?**
- During the past three months, that is since {January 2}, were you **poisoned by swallowing or breathing in a harmful substance such as bleach, carbon monoxide, or too many pills or drugs****?**
**Did you ****talk to or see a medical professional ****about this {injury/poisoning}?**

**Notes:**
So for the 2004 survey we are recommending unpacking the question and adding examples of what constitutes an injury and a poison

## What next?

**Stay tuned for whether our recommendations are implemented.**

**See more information about the survey on the NHIS website**

**Notes:**
Both discussions with the interviewers and the cognitive testing suggested that our screen question was really three questions packed into one – and that perhaps people were not hearing the injury part of the question.  So we are proposing for 2004 that the question be “unpacked”