2006-2008	

Behavioral Risk Factor Surveillance System

Asthma Call-Back Survey 

Summary Data Quality Report

	National
	Asthma
	Control
	Program

Version 1.0.0
1/15/2011

ACKNOWLEDGEMENT

The Asthma call-back Survey (ACBS) is funded by the National Asthma Control Program (NACP) in the Air Pollution and Respiratory Health Branch of the National Center for Environmental Health (NCEH). The ACBS is jointly administered with the Office of Surveillance, Epidemiology and Laboratory Services (OSELS), Division of Behavioral Surveillance (DBS).

NCEH and OSELS greatly appreciate the efforts of the BRFSS staff in each ACBS participating state.  

Paul Garbe, DVM, MPH
Chief, Air Pollution and Respiratory Health Branch
Division of Environmental Hazards and Health Effects
National Center for Environmental Health, CDC
MS F-58
4770 Buford Highway
Atlanta GA 30341
770-488-3700

Lina S. Balluz, Sc.D.
Branch Chief
Behavioral Risk Factor Surveillance System
Division of Behavioral Surveillance
Public Health Surveillance Program Office (PHSPO)
Office of Surveillance, Epidemiology and Laboratory Services (OSELS)
Centers for Disease Control and Prevention

2006-2008 Asthma Call-Back Survey (ACBS) Summary Data Quality Report 

Introduction

Procedures for interview disposition and response rates for the BRFSS Asthma Call-Back Survey (ACBS) follow usual BRFSS procedures; however, some additions and adaptations are required for the call-back survey.  Disposition codes, disposition code categories, and response rates are discussed in the sections below.  Figure one is a flow chart describing the eligibility paths BRFSS respondents with asthma follow through the ACBS process.  

Because asthma characteristics vary by season, a seasonal analysis must take into account any state for which interviewing was not conducted throughout the year.  States may have interrupted interviewing due to contract interruptions with their data collection company.  In addition, some ACBS interviews are finalized in the first few months of the next calendar year.  

Appendix A includes tables showing disposition code categories, response rates and interviews by month for each state participating in the ACBS each year.  Appendix B includes formulae for the BRFSS response rates for comparison with formulae for the ACBS rates.  More detail on BRFSS response rates and procedures can be found in the BRFSS Data Quality Report Handbook (http://www.cdc.gov/brfss/technical_infodata/surveydata.htm) and the BRFSS Summary Data Quality Report (http://www.cdc.gov/brfss/technical_infodata/quality.htm) for each survey year.  Appendix C includes additional instruction on assigning the ACBS specific disposition codes.

Disposition Codes

The usual BRFSS disposition codes are used for the ACBS.  However, a few additional codes are needed to account for situations specific to a call-back survey.  In the list below, disposition codes added for the ACBS are underlined and bolded.  Detailed descriptions of the ACBS codes can be found in Appendix C.

The ACBS disposition codes are:

I.	Eligible, contacted: complete interview

110	Complete
120	Partial complete

II.	Eligible, contacted: refusal or termination

413	Refused to participate in the call-back during the BRFSS interview
210	Terminated within the questionnaire during the ACBS interview
211	Refused to allow combining ACBS responses with BRFSS responses
212 	Refused to answer the “ever had asthma” question during the ACBS interview
220	Refused to begin the ACBS interview after contacted 

III. 	Eligible, lost to follow-up because unable to contact or communicate with the BRFSS respondent

230	Selected respondent never reached or reached but did not begin interview during interviewing period
240	Selected respondent away from residence during the entire interviewing period
250	Language problem after respondent selection
260	Selected respondent physically or mentally unable to complete an interview during the entire interviewing period
270	Hang up or termination before respondent selection
280	Household contact after number of adults recorded but before respondent selection

305	Household members away from residence during entire interviewing period
306	Selected ACBS respondent no longer living in the BRFSS household
310	Hang-up or termination, known household
315	Household contact, eligibility undetermined
320	Language problem 
325	Physical or mental impairment 
330	Hang-up or termination, unknown if private residence
332	Contact, unknown if private residence
335	Telephone answering device, message confirming private residential status
345	Telephone answering device, unknown if private residence
360	No answer
365	Busy

505	Refusal:  hang-up or termination
510	Appointment
515	Language problem
520	Physical or mental impairment
525	Answering machine, message confirming residential status
535	Answering machine, unknown if private residence
550	No answer
555	Busy

IV. 	Eligible, lost to follow-up for technical reasons

340	Telecommunication technological barrier, message confirming private residential status
350	Telecommunication technological barrier, unknown if private residence
355	Telephone number no longer in service or changed
370	On never call list

420	Not a private residence
430	Dedicated fax/data/modem line with no human contact
435	Cellular telephone
440	Fast busy
450	Non-working/disconnected number

530	Technological barrier other than answering machine, message confirming residential status
540	Technological barrier other than answering machine, unknown if private residence
545	Phone number temporarily out of service
575	Circuit busy
560	Fax/data/modem
565	Fast busy
570	Possible non-working number
580	Null attempt
585	Requires supervisor attention
599	Missing disposition code

V.	Ineligible

291	No parent or legal guardian in the household (child ineligible)

405	Out-of-state
410	Household, no eligible respondent (respondent does not have asthma)
411	Selected respondent not eligible for follow-up
412	Transferred from BRFSS but not attempted (excluded by state)
470	Misdiagnosed asthma in respondent (2008 and later)
480	Not recruited for call-back at BRFSS interview (excluded by state)
490	Random child/adult selection: adult ineligible, child selected
491	Random child/adult selection: child ineligible, adult selected

Definitions and Labels for Disposition Code Categories

Because the ACBS is a call-back interview, all those identified with asthma at the BRFSS interview asthma are, with a few notable exceptions, eligible for the call-back survey.  The ACBS eligibility flow chart (Figure 1) summarizes how BRFSS respondents are categorized for ACBS response rate calculation.  

ACBS interviews are considered complete (COIN) if the respondents finish the entire interview or if they complete through section 8 of the ACBS interview.  ACBS interviews are refusals if the respondent refuses participation at either the BRFSS interview or at the time of the ACBS interview.  Terminations are interviews that start but are terminated during the interview.  

The disposition codes that relate to contact problems or technology issues are considered “eligible, but lost to follow-up.” If they had been contacted, a small proportion of those eligible but lost to follow-up might actually be ineligible. All temporary disposition codes (numbered 500 or higher) that should have been resolved but were not are treated as comparable 400 level codes.  

BRFSS respondents with asthma who are considered ineligible for the ACBS include those who are not asked to participate at the time of the BRFSS interview. Each year between 6% and 10% of those technically eligible are not asked to participate in the call-back survey.  Respondents might not be asked for several reasons:  
•	States with split samples may only include respondents in the call-back if they are in specified splits of the BRFSS sample.  Counts for states that exclude split-sample respondents are excluded from the following tables and rate calculations.
•	 The BRFSS respondent may partially complete the BRFSS interview but terminate before the call-back request.
•	 Specific state BRFSS call-back contracts may limit the number of call-back interviews due to budgetary constraints.
•	 States may stop conducting call-back interviews during contract negotiations.  

BRFSS respondents with asthma who are asked to participate in the ACBS but are later classified as ineligible include:
•	respondents in households where  both the selected adult and selected child in the household have asthma.  When both have asthma, only one is eligible for the ACBS.  
•	respondents who move out-of-state between the BRFSS interview and the ACBS interview  
•	respondents who  indicate, at the time of the ACBS interview, that the reported diagnosis of asthma was an error  
•	child respondents for whom  the adult BRFSS respondent is not the child’s parent or guardian
•	states that have reached a pre-specified quota for interviews 

The following table indicates how disposition codes are grouped into response rate categories shown in the eligibility flow chart (Figure 1):

Category	Disposition Codes 	Notes	
Eligible COIN 
Completed interview 	110, 120	Through section 8	
Eligible TERE
Terminations and refusals 	413	At BRFSS interview	
	210, 211, 212, 220	At ACBS	
Eligible, lost to follow-up
Not interviewed	230, 240, 250, 260, 270, 280, 305, 306, 310, 315, 320, 325, 330, 332, 335, 345, 360, 365, 505, 510, 515, 520, 525, 535, 550, 555	Unable to contact or communicate with eligible respondent	
	340, 350, 355, 370, 420, 430, 435, 440, 450, 530, 540, 545, 560, 565, 570, 575, 580, 585, 599 	Technical problems	
Ineligible	291, 480, 490, 491	At BRFSS interview	
	405, 410, 411, 470 	At ACBS	
	412	No ACBS attempt	

Figure 1: ACBS Eligibility Flow Chart:

BRFSS respondent with asthma
ASTHMA2 = 1 (Yes)

Ineligible for call-back: 
•	If adult, child selected for call-back: code 490
•	If child, adult selected for call-back: code 491
•	If child, no parent/guardian:
code 291

Respondent called for ACBS interview

Permission granted

Ineligible for call-back
•	Moved out of state: code 405
•	Does not have asthma: 
code 410/470
•	Other: code 411

Ineligible for call-back
•	Never called: code 412

Recruited for call-back
Asked permission question

Ineligible for call-back: code 480
•	Split sample 
•	Quota
•	Skipped permission question

BRFSS TERE: refusal
•	Permission denied: code 413 

ACBS COIN 
•	Complete: code 110
•	Partial complete: code 120

Lost to follow-up
•	Contact/communication codes
•	Technical problem codes

ACBS TERE
•	Termination: code 210
•	Refusal: codes  211, 212, 220 

ACBS Response Rates

The ACBS Interview Completion Rate is the proportion of completed interviews among eligible respondents who are actually contacted for and started the ACBS interview. Those who refuse at the initial BRFSS interview (413), those ineligible, and those never contacted are excluded from the denominator.  This rate is based on actual contacts with the eligible respondent at the time of the call-back interview.  The numerator of the rate includes completed interviews (COIN). The denominator of the rate includes completed interviews (COIN) plus the number contacted later for the ACBS interview who refuse or terminate the interview (disposition codes 210, 211, 212, and 220).

The ACBS Cooperation Rate is the proportion of completed interviews among all eligible respondents who are recruited and actually contacted for the ACBS interview. Eligible respondents who refuse the call-back at the time of the BRFSS interview are included.  Non-contacts are excluded from the denominator, but contacts with communication problems specific to the respondent with asthma are included.  The numerator of the rate includes completed interviews (COIN).  The denominator of the rate includes completed interviews (COIN) plus refusals and terminations (TERE) plus the number of non-interviews that involved language problems with the respondent with asthma (250) or physical/mental impairment of the respondent with asthma (260). A Cooperation Rate below 65 percent may indicate some problem with interviewing techniques 

The Refusal Rate is the percentage of all eligible respondents that refuse to be interviewed or terminate an interview early in the questionnaire. The numerator includes terminations and refusals (TERE).  The denominator is the same as for the CASRO rate (below).  The denominator includes completed interviews (COIN), terminations and refusals (TERE), and a proportion of those eligible but lost to follow-up.  The proportion represents an estimate of the number of those lost to follow-up who would be expected to remain eligible if they had been contacted. The proportion of cases lost to follow-up that are estimated to be eligible is the same as the proportion of cases not lost to follow-up that are eligible.  A Refusal Rate above 35 percent indicates some problem with interviewing techniques.  

The Council of American Survey Research Organizations (CASRO) rate is a measure of respondent cooperation and is generally defined as the proportion of all eligible respondents in the sample for whom an interview has been completed.  The numerator of the CASRO rate includes completed interviews (COIN).  The denominator includes completed interviews (COIN), terminations and refusals (TERE), and a proportion of those eligible, but lost to follow-up.  The proportion represents an estimate of the number  of those lost to follow-up who would be expected to remain eligible if they had been contacted. The proportion of cases lost to follow-up that are estimated to be eligible is the same as the proportion of cases not lost to follow-up that are eligible.  A CASRO rate below 40% should be cause for a review of data collection practices that could impact it, especially sample management and interviewer recruitment, retention, training, supervision, and monitoring.

Response rate formulae for the ACBS are specified below.   Response rate tables for the ACBS, including response rates for each state participating in the ACBS, can be found in Appendix A.  Response rate formulae for the BRFSS can be found in Appendix B

Response Rate Formulae for the ACBS

ACBS Interview Completion Rate:

110 + 120

110 + 120 + 210 + 211 + 212 + 220

ACBS Cooperation Rate:

     	                                 110 + 120   
	  		 
 	110 + 120 + 210 + 211 + 212 + 220 + 413 + 250 + 260 

ACBS CASRO Rate:

                                             	110 + 120
                                            		
 [ 110 + 120 + 210 + 211 + 212 + 220 + 413 ] + P * [ Eligible lost ]

 

ACBS Refusal Rate:

                                  210 + 211 + 212 + 220 + 413
                                            		
 [ 110 + 120 + 210 + 211 + 212 + 220 + 413 ] + P * [ Eligible lost ]

       			 
Where:

P (Proportion) = (COIN + ACBS TERE) / (COIN + ACBS TERE + ACBS Ineligible)

P = [(110+120) + (210+211+212+220)] / [(110+120) + (210+211+212+220) + (405+410+411+470)]

Eligible lost = 230, 240, 250, 260, 270, 280, 305, 306, 310, 315, 320, 325, 330, 332, 335, 345, 360, 365, 370, 505, 510, 515, 520, 525, 535, 550, 555, 340, 350, 355, 370, 420, 430, 435, 440, 450, 530, 540, 545, 560, 565, 570, 575, 580, 585, 599

Appendix A:

List of Tables in the 2007 BRFSS ACBS Summary Data Quality Report

Table 1.1  2006 ACBS Disposition Categories by State: Adults 
Table 1.2  2006 ACBS Disposition Categories by State: Children  

Table 1.3  2007 ACBS Disposition Categories by State: Adults
Table 1.4  2007 ACBS Disposition Categories by State: Children

Table 1.5  2008 ACBS Disposition Categories by State: Adults  
Table 1.6  2008 ACBS Disposition Categories by State: Children

Table 2.1  2006 ACBS Response Rates by State: Adults
Table 2.2  2006 ACBS Response Rates by State: Children

Table 2.3  2007 ACBS Response Rates by State: Adults
Table 2.4  2007 ACBS Response Rates by State: Children

Table 2.5  2008 ACBS Response Rates by State: Adults
Table 2.6  2008 ACBS Response Rates by State: Children

Table 3.1  2006 ACBS Completed Interviews by State and Month:  Adults
Table 3.2  2006 ACBS Completed Interviews by State and Month:  Children

Table 3.3  2007 ACBS Completed Interviews by State and Month:  Adults
Table 3.4  2007 ACBS Completed Interviews by State and Month:  Children

Table 3.5  2008 ACBS Completed Interviews by State and Month:  Adults
Table 3.6  2008 ACBS Completed Interviews by State and Month:  Children 

Appendix B: BRFSS Response Rate Formulae

BRFSS CASRO Response Rate Formula

Completes = Completed or Partially Completed Interviews 
Completes = (110+120+(210×.32))

Eligible=All respondents with known eligibility status categorized as eligible
Eligible = (110+120+210+220+230+240+250+260+270+280)

Ineligible= All respondents with known eligibility status categorized as ineligible
Ineligible=(405+410+420+430+435+440+450)

Unknown=All respondents with unknown eligibility status
Unknown=(305+310+315+320+325+330+332+335+340+345+350+355+360+365+370)

UNKNDNOM=Unknown respondents added to the denominator
UNKNDNOM = (Eligible/(Eligible + Ineligible)) × Unknown

CASRO = (Completes / (Eligible + UNKNDNOM))

BRFSS Overall Response Rate Formula

Completes = Completed or Partially Completed Interviews 
Completes = (110+120+(210×.32))

Break-offs and Refusals = ((210×.68)+220)
Known Households = (230+240+250+260+270+280+305+310+315+335)
Ineligible Households = 410
All Likely Households= (345+350+320+325+330+332+340+370+355)

Households = (Known Households+Ineligible Households+Completes+Break-offs and Refusals+(.90×All Likely Households))
Eligible Households = (.98×Households)

Overall Response Rate = (Completes/Eligible Households)

BRFSS Cooperation Rate Formula

Completes = Completed or Partially Completed Interviews 
Completes = (110+120+(210×.32))

Break-offs and Refusals = ((210×.68)+220)

Cooperation Rate = (Completes/(Completes+Break-offs and Refusals+250+260))

Appendix C:  Instructions for Assigning Additional ACBS Disposition Codes

Following are descriptions of the ACBS disposition codes adapted from standard BRFSS disposition codes and the ACBS disposition codes added to the standard set of BRFSS disposition codes.  For detailed definitions for the standard BRFSS disposition codes see the Data Quality Handbook for each survey year (http://www.cdc.gov/brfss/technical_infodata/surveydata.htm). 

I.	Eligible, contacted: complete interview 

110	   Complete
Definition: Respondent completes the ACBS interview through the last question.

120 	Partial complete
Definition: Respondent completes the ACBS interview at least through Section 8 (medications).

II.	Eligible, contacted: refusal 

210	Terminated within the questionnaire during the ACBS interview 
Definition: If the respondent is contacted for the ACBS and terminates after the interview begins (section 3) but before completing section 8, then record is considered incomplete and is assigned disposition code 210.

211	Refused to allow combining ACBS responses with BRFSS responses
Definition: Some states require that the respondent provide active approval to combine their responses from the initial BRFSS interview with their responses from the ACBS interview.  This approval may be requested at either the initial BRFSS interview or at the beginning of the ACBS interview.  If the respondent does not approve combining data from the two interviews, the record is assigned disposition code 211.

212	Refused to answer the “ever had asthma” question during the ACBS interview
Definition: The selected respondent is contacted for the ACBS interview but refuses to answer the initial asthma question.  If the respondent answers "don't know" or "refused" to the ACBS question EVER-ASTH (2.1) “Have you ever been told by a doctor or other health professional that (you have/sample child has) asthma?”, then the record is assigned code 212.

220	Refused to begin the ACBS interview after contacted 
Definition: If the selected respondent is contacted for the ACBS interview but refuses to begin the interview, then the record is assigned code 220.

413	Refused to participate in the call-back during the BRFSS interview
Definition: During the BRFSS interview, respondents who indicate they have ever been told by a doctor that they have asthma are asked if they will participate in an additional survey at a later date.  Some state Institutional Review Boards (IRBs) require that the content of the additional survey (asthma) be disclosed; other state IRBs require that the specific content not be disclosed.  Some states have multiple call-back surveys in the field and do not specify the content of any of the call-back interviews.  If a respondent refuses to participate in the call-back survey, that record is assigned disposition code 413.

III. 	Eligible, lost to follow-up because unable to contact or communicate with the BRFSS respondent

306	Selected ACBS respondent no longer living in the BRFSS household
Definition: The BRFSS respondent with asthma left the BRFSS household between the BRFSS interview and the ACBS interview. If the selected respondent (from the BRFSS) no longer lives in the BRFSS household but did live in the household during the BRFSS interview, then attempts should be made to obtain new contact information for the selected respondent, and the follow-up should be conducted using the new telephone number. If this is not possible or the household refuses to provide new contact information, then the record is assigned disposition code 306.

Refer to the Data Quality Handbook for each survey year for the definitions of all other codes in this category (http://www.cdc.gov/brfss/technical_infodata/surveydata.htm).

IV. 	Eligible, lost to follow-up for technical reasons

Refer to the Data Quality Handbook for each survey year for the definitions of all codes in this category (http://www.cdc.gov/brfss/technical_infodata/surveydata.htm).

V.	Ineligible
291	No parent or legal guardian in the household (child ineligible)
Definition: This code applies only to the child ACBS interview.  The child selected during the BRFSS interview is eligible for the ACBS (the BRFSS respondent indicated that the selected child has an asthma diagnosis).  However, ACBS child protocol requires that the BRFSS respondent must be the parent or guardian of the child to provide proxy responses for the child or to approve transfer to a more knowledgeable proxy respondent.  If the BRFSS respondent is not the parent or guardian of the selected child with asthma, the child is ineligible for the ACBS.  The child record is assigned disposition code 291.

405	Out-of-state 
Definition:  The BRFSS question that determines eligibility for the ACBS is “Have you ever been told by a doctor, nurse, or other health professional that (you have/the sample child has) asthma?” Respondents who answer “yes” are eligible for the ACBS.  If the respondent is a state resident at the time of the BRFSS interview, but moves to an out-of-state residence between the BRFSS interview and the ACBS interview, then the respondent is no longer eligible for the ACBS, and the record is assigned disposition code 405.

410	Household, no eligible respondent (respondent does not have asthma) 
Definition:  The BRFSS question that determines eligibility for the ACBS is “Have you ever been told by a doctor, nurse, or other health professional that (you have/the sample child has) asthma?” Respondents who answer “yes” are eligible for the ACBS.  If the respondent informs the ACBS interviewer that the recorded response from the BRFSS interview was in error and terminates the call, then the respondent is not eligible for the ACBS, and the record is assigned disposition code 410.  

411	Selected respondent not eligible for follow-up
Definition: If the respondent disagrees with the recorded response to the asthma question from the BRFSS interview and answers “no” to the ACBS question EVER-ASTH (2.1) “Have you ever been told by a doctor or other health professional that (you have/the sample child has) asthma?”, then the respondent is not eligible for the ACBS, and the record is assigned disposition code 411. 

412	Transferred from BRFSS but not attempted (excluded by state) 
Definition:  The BRFSS question that determines eligibility for the ACBS is “Have you ever been told by a doctor, nurse, or other health professional that (you have/the sample child has) asthma?” Respondents who answer “yes” are eligible for the ACBS.  Eligible respondents are then asked for permission to call back.  Those that agree should be called for the ACBS interview. However, if a respondent eligible to be called is transferred from BRFSS to the ACBS but never called, then the record is assigned disposition code 412. 

470	Misdiagnosed asthma in respondent (2008 and later)
Definition:  The BRFSS question that determines eligibility for the ACBS is “Have you ever been told by a doctor, nurse, or other health professional that (you have/the sample child has) asthma?” Respondents who answer “yes” are eligible for the ACBS.  However, the initial diagnosis could have been in error and changed.  This misdiagnosis is not captured by the BRFSS or ACBS.  If the respondent informs the interviewer of the misdiagnosis, the respondent is not eligible for the ACBS, and the record is assigned disposition code 470.

480	Not recruited for call-back at BRFSS interview (excluded by state)
Definition:  The BRFSS question that determines eligibility for the ACBS is “Have you ever been told by a doctor, nurse, or other health professional that (you have/the sample child has) asthma?” Respondents who answer “yes” are eligible for the ACBS.  Eligible respondents are then asked for permission to call back.  Those who agree should be called for the ACBS interview. However, if a respondent eligible to be called is not transferred from BRFSS to the ACBS and is never called, then the record is assigned disposition code 480. 

490	Random child/adult selection: adult ineligible, child selected
Definition:  If both the BRFSS respondent and the randomly selected child in the household have asthma and the BRFSS respondent agrees to the call-back interview, one or the other is randomly selected to be eligible for the call-back.  If the child is selected, the adult is ineligible, and the adult record is assigned disposition code 490.

491	Random child/adult selection: child ineligible, adult selected 
Definition:  If both the BRFSS respondent and the randomly selected child in the household have asthma and the BRFSS respondent agrees to the call-back interview, one or the other is randomly selected to be eligible for the call-back.  If the adult is selected, the child is ineligible, and the child record is assigned disposition code 491.