Lumbar Scoliosis in Postmenopausal Women Increases With Age but Is Not Associated With Osteoporosis

Janet Rubin; Rebecca J. Cleveland; Alexander Padovano; David Hu; Maya Styner; James Sanders

Disclosures

J Endo Soc. 2021;5(5) 

In This Article

Results

Patient Demographics

Baseline characteristics of participants (n = 484) are reported in Table 1. The mean age of randomly sampled participants was 77 years, with age being higher in those with osteoporosis. A diagnosis of osteoporosis was present in 25% of the sample; body weight was significantly lower in those with osteoporosis. Those with spine osteoporosis tended to be non-White race. Scoliosis (Cobb angle ≥ 10°) was present in 25% of patients and was more frequently noted in those with hip osteoporosis.

Osteoporosis in a Postmenopausal Cohort

Osteoporosis at any region of interest (defined by a T score of ≤ –2.5) was found in 22% of the group age 64 to 68 years, increasing to 32.9% in the women in the 84- to 88-year-old group (Figure 2). In all age groups, assignment of osteoporosis was more likely to be due to a low T score in the hip neck or spine, rather than in the TH. Osteoporosis diagnosed at any site was highest in women in the 84- to 88-year-old cohort, largely due to meeting criteria at the hip sites. Although hip density decreased during each decade for the hip, this was not true for spine density in the cross-sectional data.

Figure 2.

Osteoporosis by age group. Individuals randomly selected in mid-age ranges are shown. Osteoporosis at any site (T score ≤ –2.5, "Any OP") shown in the first bar set shows increased osteoporosis by age 84 to 88. The majority of the increase is due to increase at the hip neck, shown in the second bar (difference between 64 to 68 and 84 to 88, P = .013). Spine osteoporosis shows no significant increase across the age groups.

Prevalence of Scoliosis Increases Significantly With Age

Cobb angle was measured to indicate the severity of scoliosis. We noted a higher mean Cobb angle in the older age groups: The mean angle was 4.4 (SD = 7.8) in the 64 to 68 age group and was 9.7 (SD = 9.2) in the 84 to 88 age group (Figure 3A). The presence of a clinically significant Cobb angle (≥ 10°) was highest in the oldest age group; the prevalence in the 64 to 68 cohort was 11.5% (21 of 182), 27.2% in the 74 to 78 cohort (40 of 147), and 39.4% (61 of 155) in 84 to 88 cohort (Figure 3B).

Figure 3.

Cobb angle across age groups. A, Mean and median Cobb angles are shown for the selected age groups (64–65 vs 74–75: P = .001; 64–65 vs 84–85: P ≤ .001; 74–75 vs 84–85: P = .016). B, Significant Cobb angle (≥ 10°) increases with age.

Association Between T Scores and Cobb Angle

The 64- to 68-year-old cohort was held to best represent individuals unselected for osteoporosis (screening recommendations), and was primarily used to test for a relationship between osteoporosis and scoliosis. Our analysis showed a nonstatistically significant decrease in TH T score, which is the most reliable measure of osteoporosis in patients with lumbar spine sclerosis, with increasing Cobb angle in this group, (P = .123) as shown in Figure 4A, adjusted for weight and ethnicity. In the older cohorts no association was noted between TH T score (Table 2, Figure 4A) and Cobb angle in any age group. Age-adjusted TH scores are shown in Figure 4B, where all age groups were analyzed together (in these analyses, the P value is for the β coefficient, while an R 2 value < 0.05 would be significant for an association); this clarifies the lack of a measurable relationship between scoliosis and hip T score (R2 = 0.174). As well, no association with Cobb angle in this age group was identified for T scores of the FN (Figure 4C). Despite a statistical relationship in the spine (Figure 4D), the clinical significance makes interpretation difficult in an area affected by scoliosis.

Figure 4.

Cobb angle by T scores. A, There was no association of Cobb angle with total hip T scores within age groups or B, with groups combined adjusted for age and weight (R 2 = 0.174). Cobb angles for age and weight adjusted T scores of C, hip neck and D, spine.

Association of Osteoporosis Measures With Clinically Significant Scoliosis

Table 2 presents results from logistic regression models that estimate whether presence of scoliosis is associated with osteoporosis measures. Unadjusted models found an association between scoliosis BMD at the FN and TH. However, after adjusting for age and weight these were no longer statistically significant. When stratified by age group there were also no significant associations noted.

Serial Dual-energy X-Ray Absorptiometry in Available Patients

A subset of 51 patients with available serial DXA exams were analyzed for changes in Cobb angle with respect to age. The mean number of follow-up scans in this data set was 3.5 (SD = 1.4) and ranged from 2 to 7. At baseline the mean age was 73.6 (SD = 6.0) and a mean Cobb angle of 13.5 (SD = 8.9). The mean follow-up period was 4.5 years (SD = 3.4) and mean time interval between DXA exams was 4.4 years (SD = 3.5). Examination of the spaghetti plot in Figure 5 reveals high variability in individual Cobb angles over follow-up scans. Increasing age was a statistically significant predictor of increasing Cobb angle, increasing 0.70 degrees for every year increase in age (β = 0.70; SE = 0.11, P < .001).

Figure 5.

Cobb angle across time for individual patients.

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