Bariatric surgery decreases bone mineral density (BMD) at different body sites, specifically in the femoral neck and lumbar spine in adults over 40 years old and at postoperative periods greater than 12 months, according to researchers from Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China. They recommended that bone density screening and fracture prevention strategies should be emphasised for this group of patients.
For their study, ‘Changes in bone mineral density after bariatric surgery in patients of different ages or patients with different postoperative periods: a systematic review and meta-analysis’, published in the European Journal of Medical Research, the investigators sought to examine the evidence in the published literature for changes in BMD after surgery in patients with different bone sites, postoperative periods and ages.
After conducting a literature search, they identified 22 studies/articles for their systematic review and meta-analysis (3,250 people were included, 733 in the surgery group and 2,517 in the control group). In summary, regarding location the researchers found:
Thirteen articles reported on the relationship between bariatric surgery and femoral neck BMD and showed that the bone density of the surgery group significantly decreased more compared to the control group (p=0.03).
Fifteen [articles examined the relationship between bariatric surgery and lumbar spine BMD and found that the bone density of the surgery group was lower vs. the control group (p=0.26), but there was no significant difference.
Four articles reported the relationship between bariatric surgery and total body BMD and showed the bone density of the surgical group was 0.03g/cm2 lower than that of the control group (p<0.00001).
For the 12 articles assessing the association between femoral neck and bariatric surgery, there was one article in which the average age of the subjects was less than 30 years; five included 30- to 40-year-old patients; and six articles included patients older than 40 years of age.
Patients aged 30-40-year-old, bone density in the surgical group was 0.01 g/cm2 lower vs. the control group, but there was no significant difference between the results (p=0.72). For patients older than 40 years of age, there was a significant difference between the results of the surgery group and the control group (p=0.04).
Among the 12 articles assessing the association between BMD of the femoral neck and bariatric surgery, eight reported that the postoperative time was more than 12 months and two examined patients with a postoperative time of greater than 12 months.
The results showed no significant difference between the results of the surgery group and the control groups (p=0.15) and the meta-analysis results showed that the bone density in the surgery group was lower vs. the control group (p=0.03).
Of the 12 articles assessing the association between BMD of the femoral neck and bariatric surgery, the surgical approach was RYGB in six articles, not RYGB in three articles and unspecified in three articles. The results showed no significant difference between the surgery group and the control group (p=0.37) and the meta-analysis results showed that the bone density of the surgery group was lower than that of the control group, and this difference was statistically significant (p=0.03).
Among the 15 articles evaluating the relationship between bariatric surgery and the lumbar spine, the surgical approach was RYGB in five articles, not RYGB in six articles and unspecified in the remaining articles. The results showed a significant difference between the surgery and control groups (p=0.03) and the meta-analysis results showed that the bone density of the surgery group was lower than that of the control group, and this difference was statistically significant (p=0.03).
The authors concluded that longer follow-up studies are still needed to determine whether bone mass changes or stabilises.
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