Researchers looked at patients who had back surgery and found that those with low vitamin D levels before surgery had more problems afterward. People with low vitamin D were more likely to need to go back to the hospital, visit the emergency room, develop infections, and need another surgery later. The study suggests that checking vitamin D levels before back surgery might help doctors identify patients who need extra care. While this is an important finding, it doesn’t prove that vitamin D deficiency causes these problems—just that the two are connected.

The Quick Take

  • What they studied: Whether patients with low vitamin D levels before lower back surgery experience more complications after the operation
  • Who participated: Adults who had a single-level lower back fusion surgery. The study used a national network of electronic health records to find and compare patients with low vitamin D to those with normal levels
  • Key finding: Patients with low vitamin D before surgery had significantly higher rates of complications within 90 days, including hospital readmissions (19% more likely), emergency room visits (32% more likely), kidney problems (77% more likely), surgical site infections (106% more likely), and even death (140% more likely). Long-term problems like failed fusion and need for revision surgery were also more common
  • What it means for you: If you’re planning back surgery, getting your vitamin D checked beforehand might be helpful. If your levels are low, your doctor may want to monitor you more carefully after surgery or help you improve your vitamin D levels before the procedure. However, this study shows a connection, not proof that low vitamin D causes these problems

The Research Details

This was a retrospective cohort study, which means researchers looked backward at medical records of patients who had already undergone surgery. They searched a large national database of electronic health records to find adults who had a specific type of lower back surgery (single-level lumbar fusion). They then compared patients who had low vitamin D levels before surgery to those with normal vitamin D levels and tracked what happened to both groups after surgery.

The researchers looked at vitamin D levels measured before surgery and followed patients for up to 2 years after their operation. They tracked various complications including hospital readmissions, emergency room visits, infections at the surgical site, kidney problems, and whether the fusion failed (meaning the bones didn’t fuse together properly as intended).

This type of study is useful for identifying patterns and connections between factors like vitamin D levels and surgical outcomes, but it cannot prove that one thing directly causes another.

This research approach is important because it uses real-world data from many patients across different hospitals, making the findings more representative of what actually happens in practice. By looking at medical records that were already created for patient care, researchers could study a large number of people without having to conduct an expensive and time-consuming prospective study. This helps doctors understand which patients might be at higher risk for problems after surgery.

This study has several strengths: it used a large national database, looked at real patient outcomes, and tracked patients for a long time (up to 2 years). However, there are limitations to consider. The study didn’t randomly assign people to have low or normal vitamin D—it just observed what naturally occurred. This means other factors we don’t know about could explain the differences. The study also didn’t measure how much vitamin D patients had or whether correcting low vitamin D before surgery would actually prevent complications. The exact number of patients studied wasn’t provided in the abstract, which makes it harder to assess the study’s strength

What the Results Show

The main finding was that patients with low vitamin D before surgery had higher rates of complications in the first 90 days after surgery. Specifically, they were 19% more likely to be readmitted to the hospital, 32% more likely to visit the emergency room, and 77% more likely to develop acute kidney injury (a temporary loss of kidney function). Most concerning, patients with low vitamin D were twice as likely to develop surgical site infections and more than twice as likely to die within 90 days.

Beyond the first 90 days, the problems continued. Patients with low vitamin D were 47% more likely to experience pseudoarthrosis, which means the bones didn’t fuse together properly. This problem persisted at 1 year and 2 years after surgery. At 2 years, patients with low vitamin D were 69% more likely to need revision surgery (another operation to fix the original surgery).

These findings suggest that vitamin D status before surgery may be an important factor in how well patients recover. The connection between low vitamin D and complications was consistent across multiple different types of problems, which strengthens the pattern.

The study found that the increased risk of failed fusion (pseudoarthrosis) was particularly important because it lasted throughout the 2-year follow-up period. This suggests that low vitamin D may affect the body’s ability to heal the surgical site properly, not just in the immediate recovery period but for months afterward. The increased need for revision surgery at 2 years is significant because it means patients with low vitamin D were more likely to need another operation, which brings additional risks and costs

Previous research has suggested that vitamin D plays an important role in bone health, immune function, and wound healing—all critical for recovering from surgery. This study adds to that evidence by showing that the connection between low vitamin D and surgical complications appears to be real in a large group of back surgery patients. However, most previous studies were smaller or looked at different types of surgery, so this research provides new information specific to lower back fusion surgery

This study has several important limitations. First, it’s observational, meaning researchers watched what happened naturally rather than randomly assigning some patients to have low vitamin D and others to have normal levels. This means we can’t be certain that low vitamin D actually causes the complications—other factors could be responsible. Second, the study didn’t measure how low the vitamin D levels were or whether patients with extremely low levels had worse outcomes than those with moderately low levels. Third, the study didn’t track whether patients tried to improve their vitamin D levels before surgery or whether doing so would have prevented complications. Finally, the exact sample size wasn’t provided, making it difficult to fully assess how reliable the findings are

The Bottom Line

Based on this research, it appears reasonable for patients planning back surgery to have their vitamin D levels checked beforehand (moderate confidence). If levels are low, patients should discuss with their doctor whether supplementation or other ways to improve vitamin D levels before surgery might be helpful (moderate confidence). However, this study doesn’t prove that correcting vitamin D deficiency will prevent complications, so doctors should use this information as one factor among many when planning surgery and monitoring patients afterward (moderate confidence)

This research is most relevant for adults planning to have lower back fusion surgery, their surgeons, and their primary care doctors. People with known vitamin D deficiency who are considering back surgery should definitely discuss this with their surgical team. However, the findings may not apply to people having other types of surgery or to people with other spinal conditions. Patients should not delay necessary surgery to correct vitamin D levels, but rather work with their doctors to optimize their health before the procedure

If vitamin D deficiency does contribute to complications, the effects appear to happen relatively quickly—most complications occurred within the first 90 days after surgery. However, some problems like failed fusion developed over months to years. If a patient corrects their vitamin D levels before surgery, it’s unclear how long it would take for the benefits to appear, but it would likely be several weeks to months

Want to Apply This Research?

  • If you’re planning back surgery, track your vitamin D levels monthly for 3 months before your procedure. Record the actual blood test values (measured in ng/mL or nmol/L) and note any vitamin D supplements you’re taking and their dosage. This helps you and your doctor see if your levels are improving over time
  • Work with your doctor to develop a vitamin D improvement plan before surgery. This might include taking vitamin D supplements, spending more time in sunlight, or eating more vitamin D-rich foods like fatty fish, egg yolks, and fortified milk. Use the app to set reminders for taking supplements daily and to schedule follow-up blood tests
  • Create a pre-surgery health optimization timeline in the app. Set milestones for vitamin D testing at 8 weeks before surgery and again at 2 weeks before surgery. After surgery, use the app to track any symptoms that might indicate complications (fever, increased pain, swelling, difficulty urinating) and report them to your doctor immediately. Continue monitoring your vitamin D levels for at least 6 months after surgery

This research shows a connection between low vitamin D and surgical complications, but does not prove that vitamin D deficiency causes these problems. This information is for educational purposes and should not replace medical advice from your doctor. If you are planning back surgery or have been diagnosed with vitamin D deficiency, discuss these findings with your surgeon and primary care physician. Do not delay necessary surgery to correct vitamin D levels, but work with your healthcare team to optimize your health before and after your procedure. Always follow your doctor’s specific recommendations for your individual situation