The Third National Health and Nutrition Examination Survey (NHANES III), 1988-94, Series 11, No. 11A (Knee Osteoarthritis X-ray Data and Documentation) Data Release. The National Center for Health Statistics (NCHS) of the Centers for Disease Control and Prevention (CDC) collects, analyzes, and disseminates data on the health status of U.S. residents. The results of surveys, analyses, and studies are made known through a number of data release mechanisms including publications, mainframe computer data files, CD-ROMs (Search and Retrieval Software, Statistical Export and Tabulation System (SETS)), and the Internet. The National Health and Nutrition Examination Survey (NHANES) is a periodic survey conducted by NCHS. The third National Health and Nutrition Examination Survey (NHANES III), conducted from 1988 through 1994, was the seventh in a series of these surveys based on a complex, multi-stage sample plan. It was designed to provide national estimates of the health and nutritional status of the United States' civilian, noninstitutionalized population aged two months and older. This data release, Series 11 No. 11A, contains the NHANES III knee osteoarthritis X-ray data file and documentation. This data release does not replace the previous NHANES III data releases. The released data is in flat text format. A SAS program is provided to read the flat data. The user is advised to have someone who knows SAS data step to adapt the provided SAS program to his or her specific SAS environment. The following table summarizes the NHANES III data releases which are currently available. Table 1. Available NHANES III Data +----------------------+--------+---------+------------------------------------+ |Data Release Number |Release |Size in |Data Files / Description | | |Date |Megabytes| | +----------------------+--------+---------+------------------------------------+ |NHANES III, 1988-94, |October | 0.2 |Knee osteoarthritis X-ray data file | |Series 11, No. 11A, |2001 | |and documentation | |ASCII Version (This | | | | |release) | | | | +----------------------+--------+---------+------------------------------------+ |NHANES III, 1988-94, |October | 0.2 |Hepatitis C virus genotype data | |Series 11, No. 10A, |2001 | |file and documentation | |ASCII Version | | | | +----------------------+--------+---------+------------------------------------+ |NHANES III, 1988-94, |June | 240 |Raw spirometry data file and | |Series 11, No. 9A, |2001 | |documentation | |ASCII Version | | | | +----------------------+------ -+---------+------------------------------------+ |NHANES III, 1988-94, |TBA | 9.7 |Natality data file and documentation| |Series 11, No. 8A, | | |are limited to births occurring | |ASCII Version | | |within the U.S. residents and | | | | |nonresidents who were sample | | | | |persons ages 2 months and older | | | | |in the NH3 sample. | +----------------------+------ -+---------+------------------------------------+ |NHANES III, 1988-94, |June | 78.8 |Multiply Imputed Data Files and | |Multiply Imputed Data |2001 | |reports | |Set, Series 11, No. | | | | |7A, ASCII version | | | | +----------------------+--------+---------+------------------------------------+ |NHANES III, 1988-94, |January | 2.7 |Healthy Eating Index (HEI) Data File| |Series 11, No. 6A, |2000 | |and documentation includes number | |ASCII Version | | |of servings by Food Guide Pyramid | | | | |food groups and HEI | |----------------------|--------|---------|------------------------------------+ |NHANES III, 1988-94, |April | 54 |Supplemental Nutrition Survey of | |Series 11, No. 5A, |2000 | |older Americans (SNS)contains | |ASCII Version | | |subsets of individual foods | | | | |and total nutrients intake data | | | | |files and documentation | +----------------------+--------+---------+------------------------------------+ |NHANES III, 1988-94, |Septem- | 0.5 |Priority toxicant reference range | |Series 11, No. 4A, |ber 2000| |study data file and documentation | |ASCII Version | | | | +----------------------+--------+---------+------------------------------------+ |NHANES III, 1988-94, |July | 33 |Second exam sample files for | |Series 11, No. 3A, |1999 | |dietary recall, examination, | |ASCII Version | | |laboratory, additional laboratory | | | | |analytes and documentation | +----------------------+--------+---------+------------------------------------+ |NHANES III, 1988-94, |April | 407 |Dietary recall (replacement), | |Series 11, No. 2A, |1998 | |electrocardiography, laboratory | |ASCII Version | | |(additional analytes), and | | | | |vitamins/medicines data files and | | | | |documentation | +----------------------+--------+---------+------------------------------------+ |NHANES III, 1988-94, |October | 285 |Adult and youth household | |Series 11, No. 1, |1997 | |questionnaire, examination, and | |Revised SETS Version | | |laboratory data files and | |1.22a | | |documentation, plan and operation, | | | | |analytic and reporting guidelines, | | | | |weighting and estimation | | | | |methodology, field operations, | | | | |non-response bias | +----------------------+--------+---------+------------------------------------+ |NHANES III, 1988-94, |July | 454 |Adult and youth household | |Series 11, No. 1A, |1997 | |questionnaire, dietary recall, | |ASCII Version | | |examination, and laboratory data | | | | |files and documentation | +----------------------+--------+---------+------------------------------------+ |NHANES III, 1988-94, |July | 285 |Adult and youth household | |Series 11, No. 1, |1997 | |questionnaire, examination, and | |SETS Version 1.22a * | | |laboratory data files and | | | | |documentation | +----------------------+--------+---------+------------------------------------+ |NHANES III Reference |October | 152 |Plan and operation, analytic and | |Manuals and Reports |1996 | |reporting guidelines, weighting and | |October 1996 | | |estimation methodology, field | | | | |operations, non-response bias | +----------------------+--------+---------+------------------------------------+ * Do not use this CD-ROM. It had technical problems and has been superseded by the revised SETS version 1.22a, Series 11, No. 1, released in October 1997. The first release of NHANES III data is available on three different CD-ROMs. The first CD-ROM, Series 11, No. 1 SETS Version 1.22a contains data accessible through the Statistical Export and Tabulation System (SETS) retrieval software as well as documentation. This CD-ROM had technical problems and should not be used; it has been superseded by the Series 11, No. 1 Revised SETS Version 1.22a. This revised CD-ROM includes corrections to the SETS software and also contains the NHANES III Reference Manuals and Reports. A third CD-ROM, Series 11, No. 1A, contains the same data and documentation (except the Reference Manuals and Reports) as on the Series 11, No. 1 Revised Sets Version 1.22a CD-ROM plus the expanded dietary recall data and documentation. All data on the Series 11, No. 1A CD-ROM are in ASCII format only. Background information on the procedures, survey components, questionnaires, examination and laboratory methods, and statistical analysis guidelines is available on the NHANES III Reference Manuals and Reports (CD-ROM). All data users are strongly encouraged to review these reference materials and reports before analyzing NHANES III data. Guidelines for Data Users o NHANES III survey design and demographic variables are found on the Household Adult Data File, Household Youth Data File, the Laboratory Data File and the Examination Data File. In preparing a data set for analysis, other data files should be merged with either or both of the Adult Household Data File or the Youth Household Data File to obtain many important analytic variables. o All of the NHANES III public use data files are linked with the common survey participant identification number (SEQN). Merging information from multiple NHANES III data files using this variable ensures that the appropriate information for each survey participant is linked correctly. o NHANES III public use data files do not have the same number of records on each file. The Household Questionnaire Files (divided into two files, Adult and Youth) contain more records than the Examination Data File because not everyone who was interviewed completed the examination. The Laboratory Data File contains data only for persons aged one year and older. The Individual Foods Data File based on the dietary recall, the Prescription Medication Data File, and The Vitamin and Minerals Data File all have multiple records for each person rather than the one record per sample person contained in the other data files. o For each data file, SAS program code with standard variable names and labels is provided as separate text files on the CD-ROM that contains the data files. This SAS program code can be used to create a SAS data set from the data file. o Modifications were made to items in the questionnaires, laboratory, and examination components over the course of the survey; as a result, data may not be available for certain variables for the full six years. In addition, variables may differ by phase since some changes were implemented between phases. Users are encouraged to read the Notes sections of the file documentation carefully for information about changes. o Extremely high and low values have been verified whenever possible, and numerous consistency checks have been performed. Nonetheless, users should examine the range and frequency of values before analyzing data. o Some data were not ready for release at the time of this publication due to continued processing of the data or analysis of laboratory specimens. A listing of those data are available in the general information section of each data file. o Confidential and administrative data are not available or released to the public. Additionally, some variables have been recoded to protect the confidentiality of the survey participants. For example, all age-related variables were recoded to 90+ years for persons who were 90 years of age or older. o Some variable names may differ from those used in the Phase 1 NHANES III Provisional Data Release and some variables included in the Phase 1 provisional release may not appear on these files. Do not use the Phase 1 provisional release; use the current (six-year) release. o Although the data files have been edited carefully, it is possible that errors may still exist. Please notify NCHS staff (301-458-4636) of any suspected errors in the data file or the documentation. Refer to the NCHS website at http://www.cdc.gov/nchs/nhanes.htm for updates to these data files. Analytic Considerations o NHANES III (1988-94) was designed so that the survey's first three years, 1988-91, its last three years, 1991-94, and the entire six years were national probability samples. Analysts are encouraged to use all six years of survey results. o Sample weights are available for analyzing NHANES III data. One of the following three sample weights will be appropriate for nearly all analyses: interviewed sample final weight (WTPFQX6), examined sample final weight (WTPFEX6), and mobile examination center (MEC)- and home-examined sample final weight (WTPFHX6). Choosing which of these sample weights to use in any analysis depends on the variables being used. A good rule of thumb is to use "the least common denominator" approach. In this approach, the user checks the variables of interest. The variable that was collected on the smallest number of persons is the "least common denominator," and the sample weight that applies to that variable is the appropriate one to use for that analysis. For more detailed information, see the Analytic and Reporting Guidelines for NHANES III (U.S. DHHS, 1996). Referencing or Citing NHANES III Data o In publications, please acknowledge NCHS as the original data source. For instance, the reference for this Knee Osteoarthritis X-ray Data File in this release is: U.S. Department of Health and Human Services (DHHS). National Center for Health Statistics. Third National Health and Nutrition Examination Survey, 1988-1994, NHANES III Knee osteoarthritis X-ray data file (Series 11, No. 11A). Hyattsville, MD: Centers for Disease Control and Prevention, 2001. Problems Using the Data NHANES III is a wonderfully rich source of data and NCHS encourages you to use the data for research and analysis. However, the dataset is large and complex and familiarity with data file manipulation and analysis is required. NCHS does not have the personnel resources to perform analyses, check results, debug programs or do literature review for your work. Thorough review of the extensive documentation on the planning of the survey, analytic guidelines and individual datasets should resolve most questions. If you still have questions after careful review of the documentation, please contact the Data Dissemination Branch at (301)458-4636. -------------------------------------------------------------------------------- NHANES III Osteoarthritis X-Ray Component Data File Index ------------------------------------------------------------------------ Variable Description Name Positions ------------------------------------------------------------------------ Respondent identification number ............ SEQN 1-5 Kellgren-Lawrence score, right knee ......... XRPKLR 6 Kellgren-Lawrence score, left knee .......... XRPKLL 7 Osteophyte - medial femoral, right knee ..... XRPOMFR 8 Osteophyte - medial femoral, left knee ...... XRPOMFL 9 Osteophyte - medial tibial, right knee ...... XRPOMTR 10 Osteophyte - medial tibial, left knee ....... XRPOMTL 11 Osteophyte - lateral femoral, right knee .... XRPOLFR 12 Osteophyte - lateral femoral, left knee ..... XRPOLFL 13 Osteophyte - lateral tibial, right knee ..... XRPOLTR 14 Osteophyte - lateral tibial, left knee ...... XRPOLTL 15 Sclerosis - medial femoral, right knee ...... XRPSMFR 16 Sclerosis - medial femoral, left knee ....... XRPSMFL 17 Sclerosis - medial tibial, right knee ....... XRPSMTR 18 Sclerosis - medial tibial, left knee ........ XRPSMTL 19 Sclerosis - lateral femoral, right knee ..... XRPSLFR 20 Sclerosis - lateral femoral, left knee ...... XRPSLFL 21 Sclerosis - lateral tibial, right knee ...... XRPSLTR 22 Sclerosis - lateral tibial, left knee ....... XRPSLTL 23 Chondrocalcinosis - right knee .............. XRPCHOR 24 Chondrocalcinosis - left knee ............... XRPCHOL 25 Joint replacement - right knee .............. XRPJRR 26 Joint replacement - left knee ............... XRPJRL 27 NHANES III Examination Data File ------------------------------------------------------------------------ EXAMINATION XRAY DATA ------------------------------------------------------------------------ Positions Item description SAS name Counts and code Notes ------------------------------------------------------------------------ 1-5 Respondent identification number SEQN 2589 32234-53616 6 Kellgren-lawrence score, right knee XRPKLR 1294 0 Normal 246 1 Possible osteophyte 632 2 Definite osteophyte 166 3 Moderate multiple osteophytes 54 4 Large osteophytes, severe sclerosis 163 8 Blank but applicable 34 9 Unreadable 7 Kellgren-lawrence score, left knee XRPKLL 1271 0 Normal 302 1 Possible osteophyte 640 2 Definite osteophyte 141 3 Moderate multiple osteophytes 45 4 Large osteophytes, severe sclerosis 163 8 Blank but applicable 27 9 Unreadable 8 Osteophyte - medial femoral, right knee XRPOMFR 2009 0 Normal 254 1 Mild or 1-33% abnormal 93 2 Moderate or 34-66% abnormal 36 3 Severe or 67-100% abnormal 163 8 Blank but applicable 34 9 Unreadable 9 Osteophyte - medial femoral, left knee XRPOMFL 2060 0 Normal 223 1 Mild or 1-33% abnormal 88 2 Moderate or 34-66% abnormal 28 3 Severe or 67-100% abnormal 163 8 Blank but applicable 27 9 Unreadable 10 Osteophyte - medial tibial, right knee XRPOMTR 1721 0 Normal 588 1 Mild or 1-33% abnormal 77 2 Moderate or 34-66% abnormal 6 3 Severe or 67-100% abnormal 163 8 Blank but applicable 34 9 Unreadable 11 Osteophyte - medial tibial, left knee XRPOMTL 1740 0 Normal 583 1 Mild or 1-33% abnormal 68 2 Moderate or 34-66% abnormal 7 3 Severe or 67-100% abnormal 163 8 Blank but applicable 28 9 Unreadable 12 Osteophyte - lateral femoral, right knee XRPOLFR 2056 0 Normal 247 1 Mild or 1-33% abnormal 76 2 Moderate or 34-66% abnormal 13 3 Severe or 67-100% abnormal 163 8 Blank but applicable 34 9 Unreadable 13 Osteophyte - lateral femoral, left knee XRPOLFL 2091 0 Normal 229 1 Mild or 1-33% abnormal 64 2 Moderate or 34-66% abnormal 14 3 Severe or 67-100% abnormal 163 8 Blank but applicable 28 9 Unreadable 14 Osteophyte - lateral tibial, right knee XRPOLTR 1939 0 Normal 366 1 Mild or 1-33% abnormal 74 2 Moderate or 34-66% abnormal 13 3 Severe or 67-100% abnormal 163 8 Blank but applicable 34 9 Unreadable 15 Osteophyte - lateral tibial, left knee XRPOLTL 1974 0 Normal 361 1 Mild or 1-33% abnormal 55 2 Moderate or 34-66% abnormal 8 3 Severe or 67-100% abnormal 163 8 Blank but applicable 28 9 Unreadable 16 Sclerosis - medial femoral, right knee XRPSMFR 2018 0 Normal 332 1 Mild or 1-33% abnormal 35 2 Moderate or 34-66% abnormal 2 3 Severe or 67-100% abnormal 163 8 Blank but applicable 39 9 Unreadable 17 Sclerosis - medial femoral, left knee XRPSMFL 2014 0 Normal 346 1 Mild or 1-33% abnormal 33 2 Moderate or 34-66% abnormal 3 3 Severe or 67-100% abnormal 163 8 Blank but applicable 30 9 Unreadable 18 Sclerosis - medial tibial, right knee XRPSMTR 1951 0 Normal 385 1 Mild or 1-33% abnormal 47 2 Moderate or 34-66% abnormal 4 3 Severe or 67-100% abnormal 163 8 Blank but applicable 39 9 Unreadable 19 Sclerosis - medial tibial, left knee XRPSMTL 1938 0 Normal 403 1 Mild or 1-33% abnormal 48 2 Moderate or 34-66% abnormal 7 3 Severe or 67-100% abnormal 163 8 Blank but applicable 30 9 Unreadable 20 Sclerosis - lateral femoral, right knee XRPSLFR 2276 0 Normal 94 1 Mild or 1-33% abnormal 20 2 Moderate or 34-66% abnormal 163 8 Blank but applicable 36 9 Unreadable 21 Sclerosis - lateral femoral, left knee XRPSLFL 2311 0 Normal 73 1 Mild or 1-33% abnormal 13 2 Moderate or 34-66% abnormal 163 8 Blank but applicable 29 9 Unreadable 22 Sclerosis - lateral tibial, right knee XRPSLTR 2246 0 Normal 119 1 Mild or 1-33% abnormal 24 2 Moderate or 34-66% abnormal 1 3 Severe or 67-100% abnormal 163 8 Blank but applicable 36 9 Unreadable 23 Sclerosis - lateral tibial, left knee XRPSLTL 2293 0 Normal 88 1 Mild or 1-33% abnormal 16 2 Moderate or 34-66% abnormal 163 8 Blank but applicable 29 9 Unreadable 24 Chondrocalcinosis - right knee XRPCHOR 2207 0 Absent 185 1 Present 163 8 Blank but applicable 34 9 Unreadable 25 Chondrocalcinosis - left knee XRPCHOL 2228 0 Absent 168 1 Present 163 8 Blank but applicable 30 9 Unreadable 26 Joint replacement - right knee XRPJRR 2393 0 Absent 29 1 Present 163 8 Blank but applicable 4 9 Unreadable 27 Joint replacement - left knee ; XRPJRL 2399 0 Absent 26 1 Present 163 8 Blank but applicable 1 9 Unreadable NHANES III KNEE OSTEOARTHRITIS X-ray Data Special Notes This "Special Notes" specific to the Knee Osteoarthritis X-ray Data File is divided into four main sections. The first section, "General Information," provides information about the file contents. The second section, "NHANES III X-ray Component Index," includes a brief description of each variable in the data set, the variable name and the item position. The third section, "NHANES III Examination Data File; Item Descriptions, Codes, Counts, and Notes" provides the variable name, a brief description of the possible values for that variable, a frequency count for each value, notes by variable, and appendices as necessary. "References" are provided in the fourth section. GENERAL INFORMATION The analysis of NHANES III knee osteoarthritis data must be conducted in the context of the key survey design and basic demographic variables. The NHANES III Household Adult Questionnaire Data File (ages 17 years and older) contains demographic data, health indicators, functional health status and other related information collected during household interviews. The NHANES III Household Adult Examination Data File (ages 17 years and older) contains physician’s examination of theses joints and other related information. They also contain all survey design variables and sample weights for these age groups. These files may be linked to the knee osteoarthritis x-ray data file using the unique survey participant (sample person) identifier SEQN. Scope of Data Release Only Phase 2 (1991-1994) knee radiographs were read for osteoarthritis in NHANES III and are contained in this data release. Therefore, when analyzing data for these readings, the MEC Phase 2 sample weight should be used (WTPFEX2). For more information on the use of sample weights in NHANES III data analysis, refer to the NHANES III Analytic and Reporting Guidelines (U.S. DHHS, 1996b). At the time of this data release, hand osteoarthritis x- ray results were not available. NHANES III hand and knee radiographs have also not been read for any other types of arthritis. Radiograph Collection Non-weight bearing anteroposterior knee radiographs (x-rays) were collected on examinees aged 60 years and older at the mobile examination center (MEC). There were no medical, safety or other exclusions in the protocol for this component. All examinees who were able to self transfer to the x-ray table, or who could be assisted in transferring by someone who accompanied them, were eligible. No radiographs were taken on examinees who did not travel to the MEC. There was an overall 93% completion rate for obtaining radiographs from participants who were examined (see table A.8, Analytic and Reporting Guidelines U.S. DHHS, 1996b). Reasons for incomplete tests or tests not done included: 1. hardware malfunction or lack of supplies; 2. insufficient time available or room not available; 3. examinee refused or uncooperative; 4. examinee unable to physically cooperate. For those examinees, osteoarthritis knee x-ray results were coded as ‘8 - Blank but applicable’. Detailed radiograph collection and processing instructions are discussed in the X-ray Procedures Manual (U.S. DHHS, 1996). The MEC physicians reviewed all x-rays both for technique and for abnormal findings. Abnormal findings were forwarded for an expedited reading by a contract radiologist and triggered a report of findings letter to inform the participant. For quality control purposes, using an observation checklist, the radiology consultant periodically observed a sample of x-rays taken by technicians. Feedback was provided on a regular basis to technicians. Radiographic Atlases, Scoring Systems, Reader Training and Reading Protocols In order to obtain global and individual radiographic features (IRF) readings for knee OA, the Kellgren-Lawrence (KL) atlas for knee OA (1) and the Osteoarthritis Research Society atlas of individual radiographic features of OA (2) were used, respectively. In addition, presence or absence of chondrocalcinosis and joint replacement were noted. Joint replacement included the presence of arthroplastic orthopedic hardware related to the articular surface. Radiographs were considered unreadable for a feature if there was inadequate coverage of the anatomy, motion, rotation, incorrect positioning, or over- or under-exposure, and coded in the dataset as ‘9 - unreadable’. Less than two percent of radiographs were unreadable for any feature. Evidence of disease for the global scores was defined as a Kellgren- Lawrence score of =2, where grade 2 equals the presence of definite osteophytes (with or without possible joint space narrowing, since these are non-weight bearing radiographs). Evidence of disease for IRF (osteophytes and sclerosis) were defined as scores = 1 which represented at least mild (1-33%) abnormality. Evidence of chondrocalcinosis and joint replacement were defined as scores = 1 which represented presence of disease. Two radiologists were trained in the radiograph scoring methods by an expert musculoskeletal radiologist. The standardized approach for reading the study radiographs included a single reading on all radiographs by one qualified reader. Additionally, all radiographs showing any evidence of disease, plus a random sample of radiographs from 10% of non-affected individuals were read by a second reader. Three sets of quality control (QC) radiographs with an equal representation of normal to advanced disease were selected from the study population by the project coordinator for use in intra- and inter-reader reliability assessment. Kappa statistics were used to assess reader reliability for the presence of disease (KL grade 2-4; osteophytes grade 1-3; and sclerosis grade 1-3) versus non-disease (KL grade 0-1; osteophytes grade 0; and sclerosis grade 0). Kappas for inter-rater agreement were > 0.71 for the KL scores, > 0.70 for the IRF osteophyte scores, > 0.50 for sclerosis, and > 0.57 for chondrocalcinosis scores. Kappas for intra-rater agreement for the primary reader were > 0.84 for the KL scores, > 0.80 for the IRF osteophyte scores, > 0.68 for sclerosis, and > 0.80 for chondrocalcinosis scores. Kappas for intra-rater agreement for the secondary reader were > 0.82 for the KL scores, > 0.71 for the IRF osteophyte scores, > 0.58 for sclerosis, and > 0.53 for chondrocalcinosis scores. Once all readings were completed by both readers, consensus readings were conducted on radiographs showing disagreement between the two qualified readers by major differences: at least two grades for KL global scores, or IRF osteophyte or sclerosis scores; or presence or absence of minimal disease: a) between grades 1 and 2 for KL global scores, or b) between grades 0 and 1 for osteophyte or sclerosis IRF scores or chondrocalcinosis. Concensus readings (for at least one radiographic feature) were performed on 35.6% of the x-rays. For all other reading differences for KL, osteophyte and sclerosis scores, reader 1 scores were used as final. REFERENCES 1. Atlas of standard radiographs of arthritis. In: The Epidemiology of Chronic Rheumatism. Vol II. Philadelphia, FA Davis Company, 1963. 2. Altman RD, Hochberg MC, Murphy WA, Jr., Wolfe F, Lequesne M: Radiographic atlas of the hand, hip and knee. Osteoarthritis Cart 1995;3(Suppl A):3-70.