Vertebral Compression Fractures in Patients with Chronic Lymphocytic Leukemia: Incidence and Risk Factors
Authors: Desai Amrita , Kuritzky Benjamin , Castillo Jorge J , Olszewski Adam J. 
Published: October 2019

Abstract
Abstract 4586

Introduction:
Patients with chronic lymphocytic leukemia (CLL) have infiltrative bone marrow changes in vertebral bodies on radiographic studies. Whether CLL is associated with an increased risk of compression fracture and/or osteoporosis in correlation with the burden or duration of the disease has not been studied. For this purpose, we performed a retrospective case-control study.

Methods:
After obtaining Institutional Review Board approval, we reviewed the records of CLL patients managed in our centers with watchful waiting from diagnosis until treatment. Data on demographic, clinical and laboratory variables, radiographic findings and treatment were collected. Presence of osteoporosis and compression fractures was ascertained from physician evaluation notes, bone densitometry studies and/or computed tomography (CT) scan results prior to initiation of chemotherapy. CLL cases were matched by age, sex and body mass index (BMI) at 1:2 ratio to healthy controls derived from a local Family Practice database. Cox regression models were used for the evaluation of hazard ratios (HR) and 95% confidence intervals (CI) for factors associated with compression fractures in patients with CLL undergoing a watchful waiting approach.

Results:
Among 96 CLL cases included in the analysis there were 48% women, 10% current and 34% former smokers. The median age was 71 years (range, 44–99), median BMI 26 (18–50) and median follow up time 2.9 years (0–22, with the last follow up between 2003 and 2012). The median absolute lymphocyte count (ALC) was 40,850/mm3 (5,700–969,000/mm3), mean hemoglobin 12.4 g/dL (+/− 2.2 g/dL), lactate dehydrogenase 202 IU/L (+/− 95 IU/L), 25-OH-vitamin D 30.7 ng/mL (+/− 12.3 ng/mL). Staging CT scans were available in 68% of cases, but bone density scans only in 13% (2% men, 24% women). Chemotherapy was started in 41% of patients after a median time of 2.4 years from diagnosis.
Osteoporosis and osteopenia were each recorded in 12% of patients while a vertebral compression fracture was present in 7%. With marked differences in the availability of evaluation tests (e.g. bone density, p<0.001) and length of period of observation between CLL cases and matched controls, there was no significant difference in the odds of compression fracture (odds ratio 1.0, 95%CI 0.32–2.84, p=1.0).
In the time-to-event analysis, the rate of compression fracture occurrence was 1.7% per year (95%CI 0.8–3.6%). Compression fractures in CLL patients were associated with underlying osteoporosis or osteopenia (HR 12.8, 95%CI 1.5–109, p=0.004), ALC over 100,000/mm3 (HR 5.1, 95%CI 1.1–23.7, p=0.04) and anemia, defined as hemoglobin less than 12 g/dL (HR 8.9, 95%CI 1.1–74, P=0.01, Fig.1).

Conclusions:
CLL patients managed with watchful waiting may be at risk of vertebral compression fractures proportional to the burden of disease. Further prospective research may delineate potential role for screening for osteoporosis and prevention of osteoporosis and vertebral fractures in this population.

Disclosures:
No relevant conflicts of interest to declare.