title: Systematic literature review of imaging features of spinal degeneration in asymptomatic populations.
abstract: OBJECTIVE
  Degenerative changes are commonly found in spine imaging but often occur in pain-free individuals as well as those with back pain. We sought to estimate the prevalence, by age, of common degenerative spine conditions by performing a systematic review studying the prevalence of spine degeneration on imaging in asymptomatic individuals.
  
  
  METHODS
  We performed a systematic review of articles reporting the prevalence of imaging findings (CT or MR imaging) in asymptomatic individuals from published English literature through April 2014. Two reviewers evaluated each manuscript. We selected age groupings by decade (20, 30, 40, 50, 60, 70, 80 years), determining age-specific prevalence estimates. For each imaging finding, we fit a generalized linear mixed-effects model for the age-specific prevalence estimate clustering in the study, adjusting for the midpoint of the reported age interval.
  
  
  RESULTS
  Thirty-three articles reporting imaging findings for 3110 asymptomatic individuals met our study inclusion criteria. The prevalence of disk degeneration in asymptomatic individuals increased from 37% of 20-year-old individuals to 96% of 80-year-old individuals. Disk bulge prevalence increased from 30% of those 20 years of age to 84% of those 80 years of age. Disk protrusion prevalence increased from 29% of those 20 years of age to 43% of those 80 years of age. The prevalence of annular fissure increased from 19% of those 20 years of age to 29% of those 80 years of age.
  
  
  CONCLUSIONS
  Imaging findings of spine degeneration are present in high proportions of asymptomatic individuals, increasing with age. Many imaging-based degenerative features are likely part of normal aging and unassociated with pain. These imaging findings must be interpreted in the context of the patient's clinical condition.
authors.affiliation: From the Department of Radiology (W.B., P.H.L., J.T.W., D.F.K.), Mayo Clinic, Rochester, Minnesota.
authors.forename: W
authors.initials: W
authors.lastname: Brinjikji
authors.affiliation: From the Department of Radiology (W.B., P.H.L., J.T.W., D.F.K.), Mayo Clinic, Rochester, Minnesota luetmer.patrick@mayo.edu.
authors.forename: P H
authors.initials: PH
authors.lastname: Luetmer
authors.affiliation: Departments of Biostatistics (B.C.) Radiology (B.C., B.W.B., L.E.C., K.J., J.G.J.).
authors.forename: B
authors.initials: B
authors.lastname: Comstock
authors.affiliation: Radiology (B.C., B.W.B., L.E.C., K.J., J.G.J.).
authors.forename: B W
authors.initials: BW
authors.lastname: Bresnahan
authors.affiliation: Radiology (B.C., B.W.B., L.E.C., K.J., J.G.J.).
authors.forename: L E
authors.initials: LE
authors.lastname: Chen
authors.affiliation: Departments of Family Medicine, Medicine, and Public Health and Preventive Medicine and the Oregon Institute of Occupational Health Sciences (R.A.D.), Oregon Health and Science University, Portland, Oregon.
authors.forename: R A
authors.initials: RA
authors.lastname: Deyo
authors.affiliation: Department of Radiology (S.H.), Henry Ford Hospital, Detroit, Michigan.
authors.forename: S
authors.initials: S
authors.lastname: Halabi
authors.affiliation: Psychiatry and Behavioral Sciences (J.A.T.).
authors.forename: J A
authors.initials: JA
authors.lastname: Turner
authors.affiliation: Department of Radiology (A.L.A.), University of California, San Francisco, San Francisco, California Division of Research (A.L.A.), Kaiser Permanente, Northern California, Oakland, California.
authors.forename: A L
authors.initials: AL
authors.lastname: Avins
authors.affiliation: Radiology (B.C., B.W.B., L.E.C., K.J., J.G.J.).
authors.forename: K
authors.initials: K
authors.lastname: James
authors.affiliation: From the Department of Radiology (W.B., P.H.L., J.T.W., D.F.K.), Mayo Clinic, Rochester, Minnesota.
authors.forename: J T
authors.initials: JT
authors.lastname: Wald
authors.affiliation: From the Department of Radiology (W.B., P.H.L., J.T.W., D.F.K.), Mayo Clinic, Rochester, Minnesota.
authors.forename: D F
authors.initials: DF
authors.lastname: Kallmes
authors.affiliation: Radiology (B.C., B.W.B., L.E.C., K.J., J.G.J.) Neurological Surgery and Health Services (J.G.J.), Comparative Effectiveness Cost and Outcomes Research Center, University of Washington, Seattle, Washington.
authors.forename: J G
authors.initials: JG
authors.lastname: Jarvik
mesh_terms: D000375:Aging / Q000473:pathology*; D001416:Back Pain / Q000453:epidemiology / Q000473:pathology; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000453:epidemiology* / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D014057:Tomography, X-Ray Computed