body fat

INTRODUCTION — Methods for determining body composition have improved over the past 20 years, greatly increasing the accuracy and ease of making these measurements [1-4]. Body composition measurements may be useful in undernourished patients, or for identifying patients who do not have an increase in overall body fat, but who have an increase in visceral fat. This latter circumstance is associated with a substantially increased risk of heart disease and diabetes. Measurement of body composition is also instructive for assessing body changes associated with growth and development, aging (sarcopenia), and in certain disease states (eg, HIV, diabetes) [5-11].

Certain measurements, such as height, weight (to calculate body mass index), and waist circumference are the minimal clinical criteria for evaluating the overweight patient. This topic will review body composition and critique most methods available for its measurement. Other considerations when evaluating the overweight patient are discussed elsewhere. (See "Screening for and clinical evaluation of obesity in adults".)

MODELS OF BODY COMPOSITION — Body composition can be viewed from five perspectives (figure 1) [1,12]:

Atomic
Molecular
Cellular
Tissues
Whole body

Atomic composition — A reference human weighing 70 kg contains 61 percent oxygen, 23 percent carbon, 10 percent hydrogen, 2.6 percent nitrogen, 1.4 percent calcium, and less than 1 percent all other atoms (phosphorous, sulphur, potassium, sodium, chlorine, magnesium, and various trace elements). Thus, six elements - oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorous - account for more than 98 percent of body mass, while less than 2 percent is contributed by the other 44 elements that are present [1].

Molecular composition — The molecular model is the most common form in which body composition is expressed. More than 100,000 chemical compounds can be identified in the human body, ranging from simple to very complex; water, lipid, and protein are the major components (figure 1) [1].

Water comprises 60 percent or more of the reference male (and 50 percent of the reference female), of which approximately 26 percent is extracellular and 34 percent intracellular.
Body fat ranges from under 10 percent in well-trained athletes to slightly over 50 percent in obese patients. Two to three percent of lipids in fat are essential structural lipids; the remainder are fat stores.
Protein comprises 15 percent of normal body composition.
Mineral comprises 5 percent of normal body composition.

Thus, water, lipid, protein, and minerals account for 99.4 percent of the molecular constituents of the body.

Cellular composition — The body is composed of cell mass, extracellular fluid, and extracellular solids. The 10(18) cells in the body of an adult can be divided into four major categories: connective tissue cells, epithelial cells, neural cells, and muscle cells. Fat cells, osteoclasts, osteoblasts, and the cellular elements of blood are components of connective tissue. Muscle cells include skeletal muscle, smooth muscle, and cardiac muscle. Epithelial cells include the cells lining a hollow viscus. The body content of potassium, measured as the naturally occurring isotope (40K) or as exchangeable potassium (42K), is the most widely used indicator of body cell mass because potassium is the principal intracellular cation [1].

Extracellular fluid is approximately 94 percent water. It is distributed into two main compartments, the plasma in the intravascular space and the interstitial fluid in the space outside of the vascular compartment. Plasma and interstitial fluid account for approximately 5 and 20 percent, respectively, of body weight in the reference human.

Tissue and organ components — Body weight represents the sum of the muscle tissue, connective tissue, epithelial tissue, and nervous tissue. Bone, adipose tissue, and muscle make up 75 percent of body weight (figure 1). The majority of body fat (80 percent in men, 90 percent in women) is subcutaneous. However, fat also accumulates around the abdominal organs (visceral fat). Visceral adipose tissue is more difficult to measure [13]. Visceral adiposity is associated with a greater risk of metabolic and cardiovascular disorders including insulin resistance, type 2 diabetes mellitus, hypertension, and coronary heart disease. (See "Health hazards associated with obesity in adults".)

Whole body — The whole body represents the final perspective on body composition. There are at least 10 different components of the whole body that may be measured, including stature, segment lengths, circumferences, skinfold thicknesses, body surface area, body volume, body weight, body mass index, and body density.

METHODS OF MEASURING BODY COMPOSITION — There are several methods for determining body composition. Each provides a different view of the body's components. The various methods include two compartment models (fat and non-fat, aqueous and non-aqueous), three compartment models (fat, lean, bone mineral), or four compartment models (body density, weight, water, and bone mineral mass) [14,15]. They differ in ease of determination, cost, accuracy, use of radiation, and utility for assessing regional body fat (table 1). The most useful techniques are described below.

Anthropometric measurements

Height and weight are the most commonly measured and can be determined with great accuracy. They are important in making clinical decisions regarding treatment of obesity [16]. Weight can be related to height by several methods, but the most widely used is the body mass index (BMI), which is weight (in kilograms) divided by the height (in meters) squared (table 2A-B). (See "Screening for and clinical evaluation of obesity in adults".)
Waist circumference is another essential anthropometric measurement. It is measured with a flexible tape placed on a horizontal plane at the level of the iliac crest as seen from the anterior view (figure 2). Increasing central adiposity, as measured by waist circumference, is associated with an increased risk of morbidity and mortality. (See "Screening for and clinical evaluation of obesity in adults", section on 'Waist circumference' and "The metabolic syndrome (insulin resistance syndrome or syndrome X)".)
Measurements of skinfold thickness are considerably less accurate than measurements of height or weight, particularly in obese subjects. Thus, they have little practical clinical value and are primarily used in epidemiological studies.

Dual-energy X-ray absorptiometry — Dual-energy X-ray absorptiometry (DXA) is one of the more commonly used methods for determining body composition. This method is based on the attenuation of signals from two energy sources to provide a three compartment model of body composition.

In a study comparing DXA with a four compartment model of body composition, estimates of mean percent body fat were similar between the two methods [15]. However, there was considerable intraindividual variability, ranging from -3.0 to +4.0 percent, with DXA. Thus, DXA is good for cross-sectional measurements, but is less reliable for individual measures.

Isotopic measurement of body water — Isotopic dilution with a tracer that measures body water (D20; 3H20) also provides an accurate assessment of body fat. In a study of children, three methods (DXA, isotopic measurement of body water, and densitometry) provided a similar estimate of body fat relative to a more complicated four-compartment model of body composition [1,14].

Body density and whole body plethysmography — Partitioning fat and fat-free components of the body can be done with hydrodensitometry (underwater weighing) or whole body plethysmography (Bod Pod). The first technique weighs the individual on dry land and then after complete submersion, preferably with a simultaneous measurement of lung volume. In contrast, whole body plethysmography uses air displacement rather than water displacement to measure body fat. It is similar in principle to hydrodensitometry or underwater weighing, but does not require submersion. In a study that compared air displacement (Bod Pod) versus water displacement (underwater weighing), the two methods were highly correlated (r = 0.94) with a standard error of the estimate of 0.0073 [17]. Air displacement appears to be an important new instrument for measurement of body fat.

Impedance measurement — Impedance measurement is widely used but has significant limitations. Impedance is measured by applying electrodes to one arm and one leg or by standing on the foot plates of a special scale. Impedance is proportional to the length of the conductor and inversely related to the cross-sectional area of the conductor. Accuracy in placement of electrodes is essential because even small variations can cause relatively large errors in the measurement of impedance and corresponding errors in the estimate of body water.

A variety of formulas have been developed to convert impedance, which measures body water, into an estimate of fat [18,19]. Most formulas for estimating fat from bioelectric impedance analysis underestimate body fat [14]. As an example, in a study comparing two bioelectric impedance devices with DXA for the measurement of body fat, percent body fat measured with both bioelectric impedance devices was 2 to 6 percent lower in men and women with normal BMI [18]. Among the overweight individuals, the values were lower in women but similar in men. When using bioelectric impedance devices, it is important to use validated formulas to estimate body fat [18].

Imaging techniques — Patterns of body fat distribution can be reliably determined by either computed tomography (CT) or magnetic resonance imaging (MRI) [1,20,21]. The most common technique is to obtain a single cross sectional image at the interspace between the fourth and fifth lumbar vertebrae. The image is used to quantitate subcutaneous and visceral fat. Images obtained between the second and third lumbar vertebrae provide similar information [22].

CT uses X-radiation and computer analysis to determine the structure of internal organs. It is possible to obtain an accuracy of less than 1 percent margin of error for body fat using a series of scans. To minimize radiation dose, however, a single cut at the L4-5 position is used clinically.
MRI requires the use of a powerful magnet that surrounds the subject. It has no risks, but takes considerably longer to perform than CT. Movement will blur the images.

The estimates of subcutaneous and visceral fat obtained by these two methods may differ in absolute terms, but the relative ranking of subjects is similar.

SUMMARY — Careful measurement of height, weight, and waist circumference are the minimal measurements needed to begin evaluation of overweight patients. (See "Screening for and clinical evaluation of obesity in adults".) If there is concern about whether fat is increased, particularly visceral fat, DXA may be beneficial. Although impedance measurements are used in many clinical settings, they do not contribute more than the methods outlined a

Meaningful use II a

Medicare and Medicaid Programs; Electronic Health Record Incentive Program--
Stage 2
AGENCY: Centers for Medicare & Medicaid Services (CMS), HHS.
ACTION: Proposed rule.
SUMMARY: This proposed rule would specify the Stage 2 criteria that eligible
professionals (EPs), eligible hospitals, and critical access hospitals (CAHs) must meet in
order to qualify for Medicare and/or Medicaid electronic health record (EHR) incentive
payments. In addition, it would specify payment adjustments under Medicare for
covered professional services and hospital services provided by EPs, eligible hospitals,
and CAHs failing to demonstrate meaningful use of certified EHR technology and other
program participation requirements. This proposed rule would also revise certain Stage 1
criteria, as well as criteria that apply regardless of Stage, as finalized in the final rule
titled Medicare and Medicaid Programs; Electronic Health Record Incentive Program
published on July 28, 2010 in the Federal Register. The provisions included in the
Medicaid section of this proposed rule (which relate to calculations of patient volume and
hospital eligibility) would take effect shortly after finalization of this rule, not subject to
the proposed 1 year delay for Stage 2 of meaningful use of certified EHR technology.
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Changes to Stage 1 of meaningful use would take effect for 2013, but most would be
optional until 2014.
DATES: To be assured consideration, comments must be received at one of the
addresses provided below, no later than 5 p.m. on [OFR--insert date 60 days after date of
publication in the Federal Register].
ADDRESSES: In commenting, please refer to file code CMS-0044-P. Because of staff
and resource limitations, we cannot accept comments by facsimile (FAX) transmission.
You may submit comments in one of four ways (please choose only one of the
ways listed):
1. Electronically. You may submit electronic comments on this regulation to
http://www.regulations.gov. Follow the "Submit a comment" instructions.
2. By regular mail. You may mail written comments to the following address
ONLY:
Centers for Medicare & Medicaid Services,
Department of Health and Human Services,
Attention: CMS-0044-P,
P.O. Box 8013,
Baltimore, MD 21244-8013.
Please allow sufficient time for mailed comments to be received before the close
of the comment period.
3. By express or overnight mail. You may send written comments to the
following address ONLY:
CMS-0044-P 3
Centers for Medicare & Medicaid Services,
Department of Health and Human Services,
Attention: CMS-0044-P,
Mail Stop C4-26-05,
7500 Security Boulevard,
Baltimore, MD 21244-1850.
4. By hand or courier. Alternatively, you may deliver (by hand or courier)
your written comments ONLY to the following addresses prior to the close of the
comment period:
a. For delivery in Washington, DC--
Centers for Medicare & Medicaid Services,
Department of Health and Human Services,
Room 445-G, Hubert H. Humphrey Building,
200 Independence Avenue, SW.,
Washington, DC 20201
(Because access to the interior of the Hubert H. Humphrey Building is not readily
available to persons without Federal government identification, commenters are
encouraged to leave their comments in the CMS drop slots located in the main lobby of
the building. A stamp-in clock is available for persons wishing to retain a proof of filing
by stamping in and retaining an extra copy of the comments being filed.)
CMS-0044-P 4
b. For delivery in Baltimore, MD--
Centers for Medicare & Medicaid Services,
Department of Health and Human Services,
7500 Security Boulevard,
Baltimore, MD 21244-1850.
If you intend to deliver your comments to the Baltimore address, call telephone
number (410) 786-1066 in advance to schedule your arrival with one of our staff
members.
Comments erroneously mailed to the addresses indicated as appropriate for hand
or courier delivery may be delayed and received after the comment period.
For information on viewing public comments, see the beginning of the
"SUPPLEMENTARY INFORMATION" section.
FOR FURTHER INFORMATION CONTACT:
Elizabeth Holland, (410) 786-1309, or Robert Anthony, (410) 786-6183, EHR Incentive
Program issues.
Jessica Kahn, (410) 786-9361, for Medicaid Incentive Program issues.
James Slade, (410) 786-1073, or Matthew Guerand, (410) 786 1450, for Medicare
Advantage issues.
Travis Broome, (214) 767-4450, Medicare payment adjustment issues.
Douglas Brown, (410) 786-0028, or Maria Durham, (410) 786-6978, for Clinical quality
measures issues.
Lawrence Clark, (410) 786-5081, for Administrative appeals process issues.
CMS-0044-P 5
SUPPLEMENTARY INFORMATION:
Inspection of Public Comments: All comments received before the close of the comment
period are available for viewing by the public, including any personally identifiable or
confidential business information that is included in a comment. We post all comments
received before the close of the comment period on the following Web site as soon as
possible after they have been received: http://www.regulations.gov. Follow the search
instructions on that Web site to view public comments.
Comments received timely will also be available for public inspection as they are
received, generally beginning approximately 3 weeks after publication of a document, at
the headquarters of the Centers for Medicare & Medicaid Services, 7500 Security
Boulevard, Baltimore, Maryland 21244, Monday through Friday of each week from 8:30
a.m. to 4 p.m. To schedule an appointment to view public comments, phone
1-800-743-3951.
Acronyms
ARRA American Recovery and Reinvestment Act of 2009
AAC Average Allowable Cost (of certified EHR technology)
AIU Adopt, Implement, Upgrade (certified EHR technology)
CAH Critical Access Hospital
CAHPS Consumer Assessment of Healthcare Providers and Systems
CCN CMS Certification Number
CFR Code of Federal Regulations
CHIP Children's Health Insurance Program
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CHIPRA Children's Health Insurance Program Reauthorization Act of 2009
CMS Centers for Medicare & Medicaid Services
CPOE Computerized Physician Order Entry
CY Calendar Year
EHR Electronic Health Record
EP Eligible Professional
EPO Exclusive Provider Organization
FACA Federal Advisory Committee Act
FFP Federal Financial Participation
FFY Federal Fiscal Year
FFS Fee-For-Service
FQHC Federally Qualified Health Center
FTE Full-Time Equivalent
FY Fiscal Year
HEDIS Healthcare Effectiveness Data and Information Set
HHS Department of Health and Human Services
HIE Health Information Exchange
HIT Health Information Technology
HITPC Health Information Technology Policy Committee
HIPAA Health Insurance Portability and Accountability Act of 1996
HITECH Health Information Technology for Economic and Clinical Health Act
CMS-0044-P 7
HMO Health Maintenance Organization
HOS Health Outcomes Survey
HPSA Health Professional Shortage Area
HRSA Health Resource and Services Administration
IAPD Implementation Advance Planning Document
ICR Information Collection Requirement
IHS Indian Health Service
IPA Independent Practice Association
IT Information Technology
MA Medicare Advantage
MAC Medicare Administrative Contractor
MAO Medicare Advantage Organization
MCO Managed Care Organization
MITA Medicaid Information Technology Architecture
MMIS Medicaid Management Information Systems
MSA Medical Savings Account
NAAC Net Average Allowable Cost (of certified EHR technology)
NCQA National Committee for Quality Assurance
NCVHS National Committee on Vital and Health Statistics
NPI National Provider Identifier
NPRM Notice of Proposed Rulemaking
ONC Office of the National Coordinator for Health Information Technology
CMS-0044-P 8
PAHP Prepaid Ambulatory Health Plan
PAPD Planning Advance Planning Document
PFFS Private Fee-For-Service
PHO Physician Hospital Organization
PHS Public Health Service
PHSA Public Health Service Act
PIHP Prepaid Inpatient Health Plan
POS Place of Service
PPO Preferred Provider Organization
PQRI Physician Quality Reporting Initiative
PSO Provider Sponsored Organization
RHC Rural Health Clinic
RPPO Regional Preferred Provider Organization
SAMHSA Substance Abuse and Mental Health Services Administration
SMHP State Medicaid Health Information Technology Plan
TIN Tax Identification Number
Table of Contents
I. Executive Summary and Overview
A. Executive Summary
1. Purpose of Regulatory Action
a. Need for the Regulatory Action
b. Legal Authority for the Regulatory Action
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2. Summary of Major Provisions
a. Stage 2 Meaningful Use Objectives and Measures
b. Reporting on Clinical Quality Measures (CQMs)
c. Payment Adjustments and Exceptions
d. Modifications to Medicaid EHR Incentive Program
e. Stage 2 Timeline Delay
3. Costs and Benefits
B. Overview of the HITECH Programs Created by the American Recovery and
Reinvestment Act of 2009
II. Provisions of the Proposed Regulations
A. Definitions Across the Medicare FFS, Medicare Advantage, and Medicaid
Programs
1. Uniform Definitions
2. Meaningful EHR User
3. Definition of Meaningful Use
a. Considerations in Defining Meaningful Use
b. Changes to Stage 1 Criteria for Meaningful Use
c. State Flexibility for Stage 2 of Meaningful Use
d. Stage 2 Criteria for Meaningful Use (Core Set and Menu Set)
B. Reporting on Clinical Quality Measures Using Certified EHRs Technology by
Eligible Professionals, Eligible Hospitals, and Critical Access Hospitals
1. Time Periods for Reporting Clinical Quality Measures
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2. Certification Requirements for Clinical Quality Measures
3. Criteria for Selecting Clinical Quality Measures
4. Proposed Clinical Quality Measures for Eligible Professionals
a. Statutory and Other Considerations
b. Clinical Quality Measures Proposed for Eligible Professionals for CY 2013
c. Clinical Quality Measures Proposed for Eligible Professionals Beginning with
CY 2014
5. Proposed Reporting Methods for Clinical Quality Measures for Eligible
Professionals
a. Reporting Methods for Medicaid EPs
b. Reporting Methods for Medicare EPs in CY 2013
c. Reporting Methods for Medicare EPs Beginning with CY 2014
d. Group Reporting Option for Medicare and Medicaid Eligible Professionals
Beginning with CY 2014
6. Proposed Clinical Quality Measures for Eligible Hospitals and Critical Access
Hospitals
a. Statutory and Other Considerations
b. Clinical Quality Measures Proposed for Eligible Hospitals and CAHs for FY
2013
7. Proposed Reporting Methods for Eligible Hospitals and Critical Access
Hospitals
a. Reporting Methods in FY 2013