Risk Factors for Osteoporotic Fracture in the National Health and Nutrition Examination Survey

2012

Date Source: 

National Health and Nutrition Examination Survey, 2007-2008 (NHANES 2007-2008)

Organizer: 

Dr. Lisa Lix of the School of Public Health at the University of Saskatchewan

Background

Osteoporosis is a condition that causes bones to become thin and porous, decreasing bone strength and leading to increased risk of breaking a bone. The most common sites of osteoporotic fracture are the wrist, spine and hip. No single cause for osteoporosis has been identified.
 

Although low bone mass (or low bone density) plays an important role in determining a person's risk of osteoporosis, it is only one of many risk factors for osteoporotic fractures. Fracture risk results from a combination of bone-dependent and bone-independent factors. Age, gender, race, excessive weight loss, nutritional status, a history of fractures, and having a parent who fractured a hip all increase the risk of fracture independent of a person's bone mineral density (BMD), and individuals with more risk factors have a higher chance of suffering a fracture. For example, men and women who have the same bone density have about the same risk of a fracture, but overall women have more fractures because they have lower bone density. Persons of African ancestry have better bone density than other races; furthermore, at the same bone density they have about 30% fewer fractures. Asians have fewer fractures than Caucasians even though their bone density is lower. Other risk factors include high body mass index (BMI), large weight loss, long-term use of certain medications such as prednisone and cortisone, smoking, high alcohol consumption, and some chronic diseases.
 

The most widely recognized test for measuring BMD is a noninvasive technology known as dual-energy x-ray absorptiometry (DXA). This technique, which uses low levels of x rays, involves passing a scanner over the body. Bone density measurement by DXA at the hip and spine is generally considered the most reliable way to diagnose osteoporosis and predict fracture risk. DXA bone densitometry records the areal BMD (g/cm2), and is routinely measured at the lumbar spine (lower portion of the spine) for the vertebrae L1 to L4. For the hip, several regions may be studied including the femoral neck, trochanter and Ward’s triangle. The results of DXA scans are usually interpreted using the World Health Organisation (WHO) definition of osteoporosis, which is a T-score less than -2.5. A T-score is computed by comparing the BMD measurement to a reference value.  
 

Data Source
 

The National Health and Nutrition Examination Survey (NHANES) is a program of studies designed to assess the health and nutritional status of adults and children in the United States. The survey is unique in several countries in that it combines interviews and physical examinations and the data are made publicly available for analysis by researchers. NHANES is a major program of the National Center for Health Statistics (NCHS). NCHS is part of the Centers for Disease Control and Prevention (CDC) and has the responsibility for producing vital and health statistics for the Nation.
 
The NHANES program began in the early 1960s and has been conducted as a series of surveys focusing on different population groups or health topics. In 1999, the survey became a continuous program that has a changing focus on a variety of health and nutrition measurements to meet emerging needs. The survey examines a nationally representative sample of about 5,000 persons each year. These persons are located in counties across the country, 15 of which are visited each year.
 

The NHANES interview includes demographic, socioeconomic, dietary, and health-related questions. The examination component consists of medical, dental, and physiological measurements, as well as laboratory tests administered by highly trained medical personnel.
 

Findings from this survey can be used to determine the prevalence of major diseases and risk factors for diseases. Information is used to assess nutritional status and its association with health promotion and disease prevention. NHANES findings are also the basis for national standards for such measurements as height, weight, and blood pressure. Data from this survey is used in epidemiological studies and health sciences research, which help develop sound public health policy, direct and design health programs and services, and expand health knowledge.
 

This case study uses data from the National Health and Nutrition Examination Survey, 2007-2008 (NHANES 2007-2008), in which 10,149 individuals of all ages were initially contacted for the survey and physical examination. Data were collected between January 2007 and December 2008.
 

Further information about the NHANES 2007-2008 program can be found at the following website: http://www.cdc.gov/nchs/nhanes/nhanes2007-2008/nhanes07_08.htm
 

Frequently Asked Questions
 

Frequently asked questions about NHANES are addressed at the following website:
 

http://www.cdc.gov/nchs/nhanes/nhanes2007-2008/faqs07_08.htm

 

Research Question: 

What are the risk factors for osteoporotic fracture?
 

Objectives
 

The primary objective is to identify predictors of osteoporotic fracture (i.e., fractures of the hip, wrist, and spine) in men and women.
 

The secondary objectives include:

·         To determine which bone mineral density (BMD) measure(s) is(are) the best predictor of osteoporotic fracture after controlling for various non-BMD risk factors.

·         To determine which BMD measure(s) is(are) the best predictor of hip fracture after controlling for various non-BMD risk factors.

·         To determine if there are differences between men and women in the BMD measure(s) that is(are) the best predictor of osteoporotic fracture after controlling for non-BMD risk factors.

 

Variables: 

Data are provided for 5,935 individuals who had a DXA scan. There are 54 variables in the dataset, which includes non-bone density risk factors, BMD measurements, and information about fractures of the hip, wrist, and spine. Survey weights and sampling unit information is also included.
 

Name of Variable

Variable Description

Variable Values

SEQN

Unique ID number assigned to each sample person

Numeric value

 

 

 

ALQ101

Had at least 12 alcoholic drinks in the last year

1=yes; 2=no; 7=refused; 9=don’t know

ALQ130

Average number of alcohol drinks/day in the last 12 months

numeric value with a maximum of 95; 777=refused; 999=don’t know; .=missing

ALQ140Q

Number of days having 5+ drinks in the last 12 months

numeric value with a maximum of 365; 777=refused; 999=don’t know; .=missing

BMXBMI

Body mass index

numeric value; .=missing

DBQ197

Past 30 day milk consumption

0=never; 1=rarely – less than once a week; 2=sometimes-once a week or more, but less than once a day; 3 = often-once a day or more; 4 = varied; 7 = refused; 9 = don’t know; . = missing

DBQ229

Regular milk use 5 times per week

1= a regular milk drinker for most or all of my life, including childhood; 2= never been a regular milk drinker; 3= milk drinking has varied over my life-sometimes I’ve been a regular milk drinker; 7=refused; 9=don’t know; .=missing

DIQ010

Doctor told you have diabetes

1=yes; 2=no; 3=borderline; 7=refused; 9=don’t know; .=missing

DID040

Age when first told you have diabetes

numeric value from 1 to 80; 666=less than 1 year; 777=refused; 999=don’t know; .=missing

DIQ220

When was diabetes diagnosed

1=3 months ago or less; 2=more than 3 months ago but not more than 6 months ago; 3=more than 6 months ago but not more than 9 months ago; 4= more than 9 months ago but not more than 12 months ago, 5=more than 12 months ago;7=refused;9=don't know; .=missing

DXX0FBMD

Total femur BMD (g/cm2)

numeric value; .=missing

DXXNKBMD

Femoral neck BMD (g/cm2)

numeric value; .=missing

DXXTRBMD

Trochanter BMD (g/cm2)

numeric value; .=missing

DXXINBMD

Intertrochanter BMD (g/cm2)

numeric value; .=missing

DXXWDBMD

Ward’s triangle BMD (g/cm2)

numeric value; .=missing

DXXL1BMD

L1 BMD (g/cm2)

numeric value; .=missing

DXXL2BMD

L2 BMD (g/cm2)

numeric value; .=missing

DXXL3BMD

L3 BMD (g/cm2)

numeric value; .=missing

DXXL4BMD

L4 BMD (g/cm2)

numeric value; .=missing

DXXOSBMD

Total spine BMD (g/cm2)

numeric value; .=missing

MCQ160A

Doctor ever said you have arthritis

1=yes; 2=no; 77777=refused; 99999=don’t know; .=missing

MCQ180A

Age when told you had arthritis

numeric value from 1 to 80; 77777=refused; 99999=don’t know; .=missing

MCQ190

Type of arthritis

1=rheumatoid arthritis; 2=osteoarthritis; 3=other arthritis; 7=refused; 9=don’t know; .=missing

MCQ160C

Doctor ever said you had coronary heart disease

1=yes; 2=no; 7=refused; 9=don’t know; .=missing

MCQ180C

Age when told you had coronary heart disease

numeric value from 1 to 80; 77777=refused; 99999=don’t know; .=missing

MCQ160L

Ever told you had any liver condition

1=yes; 2=no; 77777=refused; 99999=don’t know; .=missing

MCQ170L

Do you still have a liver condition

1=yes; 2=no; 77777=refused; 99999=don’t know; .=missing

MCQ180L

Age when told you had a liver condition

numeric value from 1 to 80; 77777=refused; 99999=don’t know; .=missing

OSQ010A

Broken or fractured hip

1=yes; 2=no; 7=refused; 9=don’t know

OSQ010B

Broken or fractured wrist

1=yes; 2=no; 7=refused; 9=don’t know

OSQ010C

Broken or fractured spine

1=yes; 2=no; 7=refused; 9=don’t know

OSQ020A

Number of times broken/fractured hip

numeric value with a maximum of 5; 7777=refused; 9999=don’t know; .=missing

OSQ020B

Number of times broken/fractured wrist

numeric value with a maximum of 7; 7777=refused; 9999=don’t know; .=missing

OSQ020C

Number of times broken/fractured spine

numeric value with a maximum of 5; 7777=refused; 9999=don’t know; .=missing

OSQ40AA

Under/over 50 when fractured hip first time

1=under 50; 2=50 or older; 7=refused; 9=don’t know; .=missing

OSQ40BA

Under/over 50 when fractured wrist first time

1=under 50; 2=50 or older; 7=refused; 9=don’t know; .=missing

OSQ40CA

Under/over 50 when fractured spine first time

1=under 50; 2=50 or older; 7=refused; 9=don’t know; .=missing

OSQ070

Ever treated for osteoporosis

1=yes; 2=no; 7=refused; 9=don’t know; .=missing

OSQ130

Ever taken prednisone or cortisone nearly every day for a month or longer

1=yes; 2=no; 7=refused; 9=don’t know; .=missing

OSQ170

Did mother ever fracture a hip

1=yes; 2=no; 7=refused; 9=don’t know; .=missing

OSQ200

Did father ever fracture a hip

1=yes; 2=no; 7=refused; 9=don’t know; .=missing

RIAGENDR

Gender

1=male; 2=female; .=missing

RIDAGEYR

Age (in years)

numeric value with a maximum of 80; .=missing

RIDRETH1

Race/ethnicity

1=Mexican American; 2=Other Hispanic; 3=Non-Hispanic white; 4=Non-Hispanic black; 5=other race; .=missing

WHD020

Current self-report weight (pounds)

numeric value; 7777=refused; 9999=don’t know; .=missing

WHD110

Self-reported weight 10 years ago

numeric value; 7777=refused; 9999=don’t know; .=missing

WHD140

Greatest self-reported weight; does not include weight during pregnancy

numeric value; 7777=refused; 9999=don’t know; .=missing

 

 

 

WTMEC2YR

Full 2 year sample weight for individuals with a medical examination (MEC)

numeric value

SDMVPSU

Masked variance pseudo PSU variable for variance estimation

numeric value

SDMVSTRA

Masked variance unit pseudo-stratum variable for variance estimation

numeric value

 

Using Survey Weights and Sampling Units
 

Analytic information can be found at the following website:
 

http://www.cdc.gov/nchs/nhanes/nhanes2003-2004/analytical_guidelines.htm

 

Data Files: 

References: 


Osteoporosis Canada website (www.osteoporosis.ca)
 

Johnell O, Oden A, Caulin F, Kanis JA. Acute and long-term increase in fracture risk after hospitalization for vertebral fracture. Osteoporos Int. 2001;12(3):207-14.
 

Kanis JA. Diagnosis of osteoporosis and assessment of fracture risk. Lancet 2002; 359: 1929-36.
 

Lindsay R, Burge RT, Strauss DM. One year outcomes and costs following a vertebral fracture. Osteoporosis Int. 2005; 16:78-85.
 

Melton LJ III, Chrischilles EA, Cooper C, Lane AW, Riggs BL. Perspective: how many women have osteoporosis? J Bone Miner Res 1992;7:1005-10.