Table of Contents

Locator Record

Title: Spirometry - Raw Curve Data (SPXRAW_F )
Contact Number: 1-866-441-NCHS
Years of Content: 2009 - 2010
First Published: December, 2011
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Spirometry and Bronchodilator examination component, NHANES 2009-10 survey. Lung Function Testing, Raw Spirometry Data Curves.
Record Source: NHANES 2009 - 2010
Survey Methodology: NHANES 2009 - 2010 is a stratified multistage probability sample of the civilian non-institutionalized population of the U.S.
Medium: NHANES Web site; SAS transport files

Component Description

For NHANES 2009-10 Spirometry data, the overall summary best test results for the most frequently used spirometric parameters are provided in the dataset SPX_F. This data should be sufficient for most analytic purposes. Advanced data analysts, however, may wish to use the raw, unedited spirometry curve data for modeling the NHANES 2009-10 Spirometry data. The dataset SPXRAW_F provides this raw spirometry curve data.

Participants eligible for spirometry performed an initial or "baseline" 1st test spirometry examination. If certain criteria were met, a subset of participants then performed a repeat 2nd test spirometry exam after inhaling a β2-adrenergic bronchodilator. Multiple individual spirometry curves were typically obtained during both the 1st and 2nd test spirometry examinations. SPXRAW_F contains the raw data for all of these individual spirometry curves.

For each individual curve that was performed, the SPXRAW_F dataset contains the administrative variables listed below plus the variable SPXRAW which contains the data points needed to plot each curve. Since this is a release of raw curve data, no editing was performed for the public release dataset.

 SEQN  Respondent Sequence Number
 SPATTYPE  Type of Test: Pre- or Post-Bronchodilator Test
 SPAMANU  Spirometry Curve Number
 SPAFACT  BPTS Correction Factor
 SPAPOS  Testing Position (Standing/Sitting)
 SPAPLAT  Plateau Achieved (Individual Raw Curve)
 SPAACC  Acceptable Maneuver (Individual Raw Curve)
 SPAQEFF  Examinee Effort (Individual Raw Curve)
 SPXPTS  Number of data points in individual raw spirometry curve
 SPXRAW  Comma-delimited raw spirometry curve data

 

Eligible Sample

Survey participants ages 6 to 79 years of age, were eligible for Spirometry. Specific exclusion criteria are described in the Documentation for the spirometry summary best test dataset SPX_F  (http://www.cdc.gov/nchs/nhanes/nhanes2009-2010/SPX_F.htm).

 

Protocol and Procedure

This is described in the Documentation for the SPX_F dataset. Spirometric testing procedures met the recommendations of the American Thoracic Society and the protocol was similar to that previously used in NHANES III (1998-1994). In addition, the same spirometers that were employed in NHANES III were used in the NHANES 2007-08 and 2009-10 data collection.

 

Quality Assurance & Quality Control

This is described in detail in the Documentation for the SPX_F dataset and in the Respiratory Health Spirometry Procedures Manual. While the great majority of spirometry studies collected in NHANES 2009-10 were of high quality, because SPXRAW_F is a release of raw unedited data, some spirometry curves listed may be of poor quality. For example, individual raw curves may show defects such as extra breaths, a cough, a large extrapolated volume or a false start to the expiratory maneuver. The variable SPAACC provided with the data file indicates whether a particular curve met ATS standards for acceptability.

 

Data Processing and Editing

Please see the SPX_F dataset Documentation and the Respiratory Health Spirometry Procedures Manual (http://www.cdc.gov/nchs/data/nhanes/nhanes_07_08/spirometry.pdf).

 

Analytic Notes

It is important to note that all spirometry curves collected in NHANES 2009-10 are provided in the SPXRAW_F dataset, including those that may be unacceptable in quality and therefore either not suitable for or questionable to use in a particular data analysis. The data for the raw spirometry curves in the variable SPXRAW is the original spirometry data collected at ATPS (Ambient Temperature Pressure Saturated) and should therefore must be converted to BTPS (Body Temperature Ambient Pressure Saturated) using the correction factor provided in the variable SPAFACT (Hankinson and Viola, 1983; NIOSH, 2003).

The raw curve data contained in the SPXRAW_F variable SPXRAW is provided as a comma-delimited string of data points each of which consists of one to three characters. Each set of characters has a numeric value between -63 and 192. These numeric values represent the change in flow volume in milliliters over a 0.01 second time interval. To obtain a volume-time estimate, sequential volume-change values are summed over the time period desired. For example, to calculate the Forced Expiratory Volume in the 1st Second (FEV1), consecutive volume-change values would be summed from the start of expiration up to and including the measured value at one second. The total number of data points in a specific comma-delimited string may vary significantly from one spirometry curve to the next depending on the duration of a particular expiratory maneuver. The variable SPXPTS provides the total number of data points in a particular data curve.

For each individual curve, a number of administrative variables are provided to assist data analysts. These include SPAPOS, the spirometry testing position (standing or seated); SPAPLAT, whether a plateau was achieved in the individual spirometry curve; SPAACC, whether the individual curve was acceptable by ATS criteria; SPAQEFF, an examinee effort rating for the individual curve; and SPXPTS, the number of data points in the individual curve.

The NHANES examination sample weights, i.e. the full sample 2-Year MEC Exam Weight (WTMEC2YR) should be used to analyze the 2009-10 spirometry data. Please refer to the NHANES Analytic Guidelines (http://www.cdc.gov/nchs/nhanes/survey_methods.htm) and the on-line NHANES Tutorial (http://www.cdc.gov/nchs/tutorials/) for further details on the use of sample weights and other analytic issues.

 

References

Codebook and Frequencies

SEQN - Respondent sequence number

Variable Name:
SEQN
SAS Label:
Respondent sequence number
English Text:
Respondent sequence number.
Target:
Both males and females 6 YEARS - 79 YEARS

SPATTYPE - Pre or Post Bronchodilator Test

Variable Name:
SPATTYPE
SAS Label:
Pre or Post Bronchodilator Test
English Text:
Pre (1st test) or Post Bronchodilator (2nd test)
Target:
Both males and females 6 YEARS - 79 YEARS
Code or Value Value Description Count Cumulative Skip to Item
Pre Pre-Bronchodilator Test 34413 34413
Bron Post-Bronchodilator Test 2008 36421
< blank > Missing 0 36421

SPAMANU - Spirometry Curve Number

Variable Name:
SPAMANU
SAS Label:
Spirometry Curve Number
English Text:
Sequence identification number for an individual spirometry curve
Target:
Both males and females 6 YEARS - 79 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 to 9 Range of Values 36421 36421
. Missing 0 36421

SPAFACT - BTPS Factor

Variable Name:
SPAFACT
SAS Label:
BTPS Factor
English Text:
Body Temperature, Ambient Pressure Saturated with Water Vapor (BTPS) Correction Factor
Target:
Both males and females 6 YEARS - 79 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1.051 to 1.129 Range of Values 36421 36421
. Missing 0 36421

SPAPOS - Testing Position (Standing/Sitting)

Variable Name:
SPAPOS
SAS Label:
Testing Position (Standing/Sitting)
English Text:
Testing Position (Standing/Sitting)
Target:
Both males and females 6 YEARS - 79 YEARS
Code or Value Value Description Count Cumulative Skip to Item
Sitting Sitting 5 5
Standing Standing 36416 36421
< blank > Missing 0 36421

SPAPLAT - Plateau Achieved

Variable Name:
SPAPLAT
SAS Label:
Plateau Achieved
English Text:
Plateau achieved in spirometry curve
Target:
Both males and females 6 YEARS - 79 YEARS
Code or Value Value Description Count Cumulative Skip to Item
Y Yes 27354 27354
N No 9067 36421
< blank > Missing 0 36421

SPAACC - Acceptable Maneuver

Variable Name:
SPAACC
SAS Label:
Acceptable Maneuver
English Text:
Acceptable Maneuver
Target:
Both males and females 6 YEARS - 79 YEARS
Code or Value Value Description Count Cumulative Skip to Item
Y Yes 33828 33828
N No 2593 36421
< blank > Missing 0 36421

SPAQEFF - Examinee Effort

Variable Name:
SPAQEFF
SAS Label:
Examinee Effort
English Text:
Examinee effort rating for the individual curve
Target:
Both males and females 6 YEARS - 79 YEARS
Code or Value Value Description Count Cumulative Skip to Item
A The curve quality attributes were acceptable 20140 20140
B The curve had a large time to peak flow or a non-repeatable peak flow 5661 25801
C The curve had either < 6 seconds of exhalation or no plateau 8027 33828
D The curve had either a cough or large extrapolated volume 2593 36421
< blank > Missing 0 36421

SPXPTS - Number of Data Points in Raw Curve

Variable Name:
SPXPTS
SAS Label:
Number of Data Points in Raw Curve
English Text:
Number of Data Points in Raw Curve
Target:
Both males and females 6 YEARS - 79 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 to 2044 Range of Values 36421 36421
. Missing 0 36421

SPXRAW - Raw Spirometry Curve Data

Variable Name:
SPXRAW
SAS Label:
Raw Spirometry Curve Data
English Text:
Comma delimited raw spirometry curve data
Target:
Both males and females 6 YEARS - 79 YEARS
Code or Value Value Description Count Cumulative Skip to Item
Raw Spirometry Curve Data Value was recorded 36421 36421
< blank > Missing 0 36421