Table 1.
Study characteristics
| Author, year | Study design | No. of patients (n men) | Age of total group in years, mean (range) | Months of follow‐up, mean (range) | Imaging modality at baseline | Imaging modality at follow‐up | Definition of DD | Definition of progression |
|---|---|---|---|---|---|---|---|---|
| Burnett et al, 199645 | Cohort study | 19 (19) | 13.6, SD 0.6 at baseline; 16.3, SD 0.6 at FU | 32.4 | MRI | MRI | Loss of disc space with any evidence of collapse, no smooth borders of both AF and NP, any evidence of disc herniation, no clear white signal of the disc | Evidence of progression from baseline to follow‐up |
| Elfering et al, 200239 | Prospective cohort study | 41 (30) | 35.90 (20‐50) | 62 (54‐72) | MRI | MRI | Pearce classificationa. Grade III to V are attributed to degeneration |
Changes with regard to disc abnormalities (ie, same, better, worse) |
| Eskola et al, 201246 | Cohort study | 166 (74) | 13.1, SD 0.4 at baseline; 15.7, SD 0.3 at FU | 32.4 (26.4‐37.2) | MRI | MRI | Signal intensity changes (0‐3; 2 or 3 for DD), or change in disc contour (0‐4; 1‐4 for DD) at one or more levels | Worsened or new decrease in disc signal intensity, new disc bulge or herniation, new endplate change, or new Modic change at ≥1 lumbar levels, compared to baseline. Significant new annular tears (AT) and significant high intensity zone lesions (HIZ) |
| Farshad‐Amacker et al, 201432 | Case‐control study | 90b | 59.4 | 59.4; SD 10.2 | MRI | MRI | Pfirrmann; ≥ grade 3 | Increase in Pfirrmann grade |
| Farshad‐Amacker et al, 201433 | Retrospective cohort study | 90 (27) | 61.3 | Median 60, range 45.6‐80.4c | MRI | MRI | Pfirrmann | Increase in Pfirrmann grade in any level for DD |
| Farshad‐Amacker et al, 201734 | Case‐control study | 90 (27) | 61.1 | 60; SD 0.8 | MRI | MRI | Pfirrmann | Increase in Pfirrmann grade from 1 towards 5 on the same level during the period of observation |
| Kerttula et al, 201247 | Cohort study | 54 (9) | 43.6 (24‐65) | 12 (11‐18) | MRI | MRI | Endplate lesions, loss of disc height, and decrease in signal intensity, posterior bulge | Increase of endplate lesions, decrease of disc height and change in disc signal intensity, increase in posterior bulge |
| Liuke et al, 200540 | Retrospective longitudinal study | 129 (129) | 44 (41‐46) | 48 | MRI | MRI | Decreased signal intensity of NP compared to signal intensity of the cerebrospinal fluid | 4‐y changes in the number of discs with decreased signal intensity of the NP |
| Makino et al, 201738 | Prospective cohort study | 84 (0)d | First MRI: 20.9 (20‐22); Second MRI 30.6 (28‐35) | 117.6 (84‐168) | MRI | MRI | Schneiderman's four‐grade classification; summation of the degeneration grades of all disc levels, with five at the minimum | Worsening of Schneiderman's grade |
| Nagashima et al, 201341 | Cohort study | 192 (192) | 15 at baseline, 17 at FU | 24 | MRI | MRI | Decreased signal intensity of NP compared to signal intensity of the cerebrospinal fluid; mean signal intensity of six discs from T12L1 to L5S1 | Decrease in mean signal intensity of the NP at the 2‐y follow‐up |
| Sharma, 200936 | Retrospective longitudinal study | 46 (13) | 53.6 (20‐88) | 31.8 (4‐69)e | MRI | MRI | Loss of signal intensity, Pfirrmann | Increase in signal‐intensity grade, increase in Pfirrmann grade |
| Sharma et al, 201137 | Retrospective longitudinal study | 63 (23) | 30; SD 6.7 | 30 (3‐85)f | MRI | MRI | Pfirrmann (>2), conspicuity of AF | Increase in Pfirrmann, increase in conspicuity of AF |
| Teraguchi et al, 201735 | Cohort study | 617 (178) | 65.4 at FU; SD 12 | 48 | MRI | MRI | Pfirrmann; ≥ 4 |
|
| Videman et al, 200643 | Cohort study | 140 (140) | 49 (35‐69) | 57.6 (48‐68.4) | MRI | MRI | Signs of disc height narrowing, disc bulging, disc herniations, high intensity zones, osteophytes, upper endplate irregularities and fatty degeneration of vertebrae, annular tears, disc herniations. Each sign was rated from 0 (normal) to 3 (most abnormal) | Progression in degenerative signs |
| Videman et al, 200842 | Longitudinal study | 134 (134) | 49 (35‐69) | 57.6 (48‐68.4) | MRI | MRI | Quantitative measures of disc height and bulging | Changes in percentage of the baseline value for each quantitative measure |
| Williams et al, 201144 | Cohort study | 468 (24) | 53.6 (40.1‐68.7) at baseline | 128.4 (91.2‐164.4) | MRI | MRI | Progressive scale of 0‐3 for disc height measured in the middle of the disc, disc signal intensity within the NP, lumbar disc extension posteriorly into the spinal canal and anterior osteophytes. 0 = normal; 3 = highly degenerate disc | Subtraction of the baseline score from the FU score, adjusted for the time interval between the two MRI scans |
Abbreviations: AF, annulus fibrosus; DD, disc degeneration; FU, follow‐up; NP, nucleus pulposus.
a
Classification based on the structure of the disc, the distinction between NP and AF, signal intensity, and disc height.
b
Seventy‐two discs in total, of which 34 discs were male.
c
Of those with progression, the control group is described separately.
d
Disc progression in 44 subjects.
e
There was a follow‐up of >1 year in 40 subjects.
f
There was a follow‐up of >6 months in 90%, and a follow‐up of >12 months in 76.2%.