SOF Online Glossary

Key terms and conventions

AA	AA is the abbreviation for African-American women. African-American women were enrolled in the study at 1997, the same time as the sixth clinic visit of the main cohort. Because the sixth clinic visit was the baseline visit for the African-American cohort, the data for the AA women are treated like a separate visit from the main cohort. The SAS variable names for the baseline AA visit are prefixed with "AA" instead of "V6" before the variable root name (see entry for "Naming convention, variables"). However, at Visit 7, data from the main and AA cohorts are not treated as separate visits (although statistics on these data are reported separately), and the AA and main cohorts’ Visit 7 variable names share the "V7" prefix convention.
BMC	Bone Mineral Content.
BMD	Bone Mineral Density (BMC/bone area).
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DXA	Dual x-ray absorptiometry (used to measure BMD). See Related: BMC, BMD, SPA
Incident	as in fracture: new fracture occuring within given time period.
Naming convention, variables	SAS variables (i.e., field names) are named such that the first two characters denote the visit at which the data were collected (e.g., "V1" for visit 1). (See entry for "AA" regarding the exception for the African-American cohort's baseline visit). The variable names of equivalent data collected at different time points share the same "Root", which is 1-6 characters long following the visit prefix. For example, the measurement for current weight (Root = "WGHT") is named "V1WGHT" at visit 1, "V2WGHT" at visit 2, etc. SOF Online often abbreviates the visit names with the "V#" convention, as you will notice in the column headings for many tables on SOF Online.
Prevalent	as in fracture: existing fracture at time of visit.
Root	When referring to variables names, the "Root" pertains to the portion of the variable name that denotes the specific measurement and remains consistent for that measurement at different timepoints (see entry for "Naming convention, variables").
SOF	Study of Osteoporotic Fractures
SPA	single photon absorptiometry (used to measure BMD). See Related: BMC, BMD, DXA