Table of Contents

Locator Record

Title: Lower Extremity Disease (Ankle Brachial Blood Pressure Index) (LEXABPI )
Contact Number: 1-866-441-NCHS
Years of Content: 1999 - 2000
First Published: June, 2002
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Ankle-Brachial Blood Pressure, lower extemity disease
Record Source: NHANES 1999 - 2000
Survey Methodology: NHANES 1999 - 2000 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

The Lower Extremity Disease examination data will be used to determine the prevalence of lower extremity disease in the U.S. population (diagnosed and undiagnosed), including those at high risk for the late complications of the disease (i.e., ulceration and amputation). The major manifestations of lower extremity disease are peripheral vascular disease and peripheral neuropathy. The Ankle Brachial Blood Pressure Index (ABPI) section of the Lower Extremity Disease component collects data on peripheral vascular disease and the Peripheral Neuropathy (LEXPN) section of the Lower Extremity Disease component collects data on peripheral neuropathy. The following documentation provides information on the ABPI section.

Eligible Sample

Participants 40 years of age and older are asked to participate in the ABPI Section of the Lower Extremity Disease examination.

Exclusion Criteria

Persons are excluded from the exam if they have bilateral amputations or weigh over 400 pounds (due to equipment limitations). The variables (SEQ040, SEQ050, WHQ020L) that record this information are found in the SEQ (Shared Exclusions) File. In addition to these exclusion criteria, some persons who were eligible for the exam (40 years of age and older) might not have received the exam due to the following multiple reasons: 1) casts, ulcers, dressings, or other conditions of the participant interfered with testing, 2) participant could not understand the test instructions, 3) participant became ill and the test could not be performed, 4) there was an equipment failure, 5) participant refused, 6) participant came late or left early from the MEC and the LED exam could not be performed, or 7) some other reason. As a result, these eligible persons will have missing data for the ABPI variables.

Protocol and Procedure

Examination Protocol

Participants lie supine on the exam table during the exam. Systolic pressure is measured on the right arm (brachial artery) and both ankles (posterior tibial arteries). If the participant has a rash or open wound on the right arm, dialysis shunt, right-sided radical mastectomy or any other condition that would interfere with accurate measurement or would cause discomfort to the participant, the left arm is used for the brachial pressure measurement. Systolic blood pressure is measured twice at each site for participants aged 40-59 years and once at each site for participants aged 60 years and older. If a health technician is unable to obtain a reading at a site they may attempt another reading at the same site after a brief resting period.

Health technicians measured brachial and tibial systolic blood pressures using blood pressure cuffs with 10cm and 12cm bladder widths. However, during the 2-year data collection, a change was made to the protocol and brachial and tibial systolic blood pressure measurements were collected using blood pressure cuffs with 9cm, 12cm, 15cm, and 18cm bladder widths. The appropriate cuff to be used on a participant was determined by the circumference of the participant’s bare upper arm at the midpoint. While the participant was standing upright, the health technician would measure the participant’s arm circumference and then refer to the table below (adapted from Human Blood Pressure Determination by Sphygmomanometery by the American Heart Association) to determine the acceptable cuff size for a given arm circumference. The same size cuff was used on the arm and both ankles.

Table. Arm circumference and acceptable cuff size
Cuff Size   Bladder width (cm)  Bladder length (cm)  Arm circumference (cm)
 Child/small adult  9 17   17-21.9
 Adults  12  22  22-29.9
 Large adults  15  32  30-37.9
 Adult thigh  18  35  38-47.9

After the appropriate cuff size was selected, the cuffs were placed on the participant’s arm and each ankle. Before the blood pressure was measured at each site, the peripheral neuropathy testing of the LED exam was performed to provide a brief resting period for stabilization of the participant’s blood pressure prior to measurement. (Note: the peripheral neuropathy protocol is described in a separate section (LEXPN).
Refer to Lower Extremity Disease Procedures Manual for further details.

Staff

A trained health technician performed the examination.

Quality Assurance & Quality Control

Inspection, calibration, and maintenance of the equipment and supplies were performed on a regular basis. Health technicians were regularly monitored by MEC supervisory staff and evaluated by outside staff two to four times per year. Data were also routinely examined by outside staff. For further details refer to the Quality Control Manual.

Analytic Notes

Please note data collection methods for ABPI section and differences in blood pressure cuffs sizes.

During the data editing process, extreme values were examined. When there was insufficient information to conclude that values were invalid, they were retained in the data set. Analysts should examine the data distribution and consider whether or not it is appropriate to include or exclude extreme values in a given analysis.

In addition to missing data for persons excluded from the exam there may be other missing data for some persons due to one of the many reasons described above under ‘exclusion criteria’ such as participant refusal, equipment failure, or technical error.
Persons aged 40-59 may have up to 2 recorded blood pressure readings at each site where as persons aged 60 and older may only have 1 recorded reading at each site. Therefore, analysts should note that for participants aged 60 and older ALL second measurements will be missing at each site. Other missing blood pressure values (either the first or second for those 40-59 or the first reading for those 60+) may have been due to one of many reasons described above under item #2 such as participant refusal, equipment failure, or technical error.

The ankle brachial blood pressure index (ABPI) was automatically calculated by the computer system. The right ABPI was obtained by dividing the mean systolic blood pressure in the right ankle by the mean blood pressure in the arm. The left ABPI was obtained by dividing the mean systolic blood pressure in the left ankle by the mean blood pressure in the arm. The mean blood pressure value for the arm and ankles are computed based on the first and second reading at each site. Since the second reading for all persons 60+ is missing the mean values are in fact the first recorded blood pressure reading at a site. This may also be true for 40-59 year old persons who have a missing value for the first or second blood pressure reading.

Special Notes on Using the Dataset

Each pressure was measured twice on participants aged 40-59, but only once for participants 60 and older. Therefore, participants aged 60 and older will have missing data for all second measurements. Any other missing blood pressure values may have been due to one of many reasons such as equipment failure, participant refusal, or technician error.

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 40 YEARS - 150 YEARS

LEAARM - Arm:

Variable Name:
LEAARM
SAS Label:
Arm:
English Text:
Arm:
English Instructions:
DEFAULT IS RIGHT.
Target:
Both males and females 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Right 2633 2633
2 Left 20 2653
8 Could not obtain 5 2658
. Missing 217 2875

LEDARMCF - brachial cuff size

Variable Name:
LEDARMCF
SAS Label:
brachial cuff size
English Text:
Brachial cuff size used for BP measurement
Target:
Both males and females 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 9 cm 20 20
2 10 cm 37 57
3 12 cm 2066 2123
4 15 cm 429 2552
5 18 cm 91 2643
8 Could not obtain 0 2643
. Missing 232 2875

LEAANKL - Ankles:

Variable Name:
LEAANKL
SAS Label:
Ankles:
English Text:
Ankle(s) tested
English Instructions:
DEFAULT IS BOTH.
Target:
Both males and females 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Right 10 10
2 Left 12 22
3 Both 2629 2651
8 Could not obtain 2 2653
. Missing 222 2875

LEDANKCF - ankle cuff size

Variable Name:
LEDANKCF
SAS Label:
ankle cuff size
English Text:
Ankle cuff size used for BP measurement
Target:
Both males and females 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 9 cm 20 20
2 10 cm 1892 1912
3 12 cm 210 2122
4 15 cm 429 2551
5 18 cm 91 2642
8 Could not obtain 0 2642
. Missing 233 2875

LEXBRP1 - Brachial SBP 1

Variable Name:
LEXBRP1
SAS Label:
Brachial SBP 1
English Text:
Brachial systolic blood pressure 1 (in millimeters of mercury)
Target:
Both males and females 40 YEARS - 150 YEARS
Hard Edits:
0.0000 to 300.0000
Code or Value Value Description Count Cumulative Skip to Item
85 to 241 Range of Values 2544 2544
. Missing 331 2875

LEXBRP2 - Brachial SBP 2

Variable Name:
LEXBRP2
SAS Label:
Brachial SBP 2
English Text:
Brachial systolic blood pressure 2 (in millimeters of mercury)
Target:
Both males and females 40 YEARS - 59 YEARS
Hard Edits:
0.0000 to 300.0000
Code or Value Value Description Count Cumulative Skip to Item
91 to 236 Range of Values 1080 1080
. Missing 1795 2875

LEXBRPM - Mean Brachial SBP

Variable Name:
LEXBRPM
SAS Label:
Mean Brachial SBP
English Text:
Mean brachial systolic blood pressure (in millimeters of mercury)
Target:
Both males and females 40 YEARS - 150 YEARS
Hard Edits:
0.0000 to 300.0000
Code or Value Value Description Count Cumulative Skip to Item
89 to 241 Range of Values 2560 2560
. Missing 315 2875

LEXLPTS1 - Left Posterior Tibial SBP 1

Variable Name:
LEXLPTS1
SAS Label:
Left Posterior Tibial SBP 1
English Text:
Left posterior tibial systolic blood pressure 1 (in millimeters of mercury)
Target:
Both males and females 40 YEARS - 150 YEARS
Hard Edits:
0.0000 to 300.0000
Code or Value Value Description Count Cumulative Skip to Item
69 to 249 Range of Values 2181 2181
. Missing 694 2875

LEXLPTS2 - Left Posterior Tibial SBP 2

Variable Name:
LEXLPTS2
SAS Label:
Left Posterior Tibial SBP 2
English Text:
Left posterior tibial systolic blood pressure 2 (in millimeters of mercury)
Target:
Both males and females 40 YEARS - 59 YEARS
Hard Edits:
0.0000 to 300.0000
Code or Value Value Description Count Cumulative Skip to Item
70 to 219 Range of Values 1009 1009
. Missing 1866 2875

LEXLPTSM - Left Mean Posterior Tibial SBP

Variable Name:
LEXLPTSM
SAS Label:
Left Mean Posterior Tibial SBP
English Text:
Left mean posterior tibial systolic blood pressure (in millimeters of mercury)
Target:
Both males and females 40 YEARS - 150 YEARS
Hard Edits:
0.0000 to 300.0000
Code or Value Value Description Count Cumulative Skip to Item
69.5 to 249 Range of Values 2250 2250
. Missing 625 2875

LEXLABPI - Left ABPI

Variable Name:
LEXLABPI
SAS Label:
Left ABPI
English Text:
Left ABPI
Target:
Both males and females 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.39 to 1.84 Range of Values 2237 2237
. Missing 638 2875

LEXRPTS1 - Right Posterior Tibial SBP 1

Variable Name:
LEXRPTS1
SAS Label:
Right Posterior Tibial SBP 1
English Text:
Right posterior tibial systolic blood pressure 1 (in millimeters of mercury)
Target:
Both males and females 40 YEARS - 150 YEARS
Hard Edits:
0.0000 to 300.0000
Code or Value Value Description Count Cumulative Skip to Item
60 to 251 Range of Values 2215 2215
. Missing 660 2875

LEXRPTS2 - Right Posterior Tibial SBP 2

Variable Name:
LEXRPTS2
SAS Label:
Right Posterior Tibial SBP 2
English Text:
Right posterior tibial systolic blood pressure 2 (in millimeters of mercury)
Target:
Both males and females 40 YEARS - 59 YEARS
Hard Edits:
0.0000 to 300.0000
Code or Value Value Description Count Cumulative Skip to Item
74 to 227 Range of Values 1017 1017
. Missing 1858 2875

LEXRPTSM - Right Mean Posterior Tibial SBP

Variable Name:
LEXRPTSM
SAS Label:
Right Mean Posterior Tibial SBP
English Text:
Right mean posterior tibial systolic blood pressure (in millimeters of mercury)
Target:
Both males and females 40 YEARS - 150 YEARS
Hard Edits:
0.0000 to 300.0000
Code or Value Value Description Count Cumulative Skip to Item
60 to 251 Range of Values 2279 2279
. Missing 596 2875

LEXRABPI - Right ABPI

Variable Name:
LEXRABPI
SAS Label:
Right ABPI
English Text:
Right ABPI
Target:
Both males and females 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.44 to 1.65 Range of Values 2268 2268
. Missing 607 2875