Percutaneous Vertebroplasty for Painful Compression Fractures in a Small Cohort of Patients with a Decreased Expectation-Related Placebo Effect due to Dementia

Selection Criteria

Institutional review board approval for a retrospective analysis of vertebroplasty results in patients with dementia was obtained. All patients with a known diagnosis of dementia were identified from a comprehensive prospectively acquired vertebroplasty data base of 791 patients. Our overall results from vertebroplasty have been previously published,⁸ but no analysis of a subgroup of patients with dementia was performed in this publication. Initially, we screened all patients in whom the chart noted cognitive impairment of any type or degree. This screen yielded a cohort of 80 patients.

We aimed to achieve a high degree of specificity for patients with dementia rather than mild cognitive impairment to minimize the expectation-related placebo effect in the observed sample. Thus, we included only patients found to have a clinical diagnosis of dementia in the medical record with supporting evidence. This included formal neuropsychologic testing or a Short Test of Mental Status (STMS) administered by a neurologist with results consistent with dementia. For patients who had neuropsychologic testing, we documented the Mattis Dementia Rating Scale (DRS), a commonly used measure of dementia, as a rough indicator of dementia severity.⁹ The neuropsychologic testing generally included objective measures of memory, language, attention, concentration, visuospatial functioning, and intelligence. Most patients with dementia have scores of <130/144 on the DRS.⁹ The STMS was designed and validated specifically for dementia assessment and is commonly used at our institution.¹⁰ With this measure, a cutoff of 29/38 has reported sensitivity and specificity exceeding 90% as a screen for dementia.¹¹ Chart reviews of clinical visits, follow-up phone calls by radiology nursing, and neuropsychological testing were performed.

Exclusion criteria included the following:

1. Patients with a clinical diagnosis of dementia without any confirming objective evidence in the form of DRS, neuropsychologic testing, or a STMS.

2. Any patient with prior vertebroplasty. This criterion eliminated selection bias for patients with initial favorable clinical outcomes who might be encouraged by caregivers to undergo a subsequent procedure, even though the patients themselves might have no recollection of previous treatments.

3. Noncommunicative patients. There is evidence that the presence, but not the degree, of pain can be accurately determined in nonverbal patients with dementia.^12–14 This criterion has been applied to other studies of pain in patients with dementia.¹⁵

All patients had radiographic evidence of a compression fracture, including marrow edema on an MR image or radiopharmaceutical uptake on a bone scan. Clinically, the subjects had pain with movement as well as point tenderness over the compression site. One patient who was included had pain localized to the fractured level with fluoroscopic examination without radiopharmaceutical uptake or marrow edema. Patients with either single- or multilevel vertebroplasty were included.

Outcome Measures

Outcome measures were assessed preprocedure, 2 hours postprocedure, and at 1 week, 1 month, 6 months, and 1 year. These measures included pain at rest and activity, mobility, and pain medication use. Lack of successful follow-up at 1 time point did not preclude subsequent follow-up. Pain medication included narcotics and/or non-narcotics. Mobility and narcotic use were not assessed 2 hours postprocedure, because a longer interval would have been required to assess a meaningful response. Follow-up was achieved with a standardized phone call by radiology nursing.

Although pain generally was assessed with a 10-point visual analog scale (VAS) in the data base, the inability of patients with dementia to consistently assign numbers to a VAS precludes a quantitative analysis of pain in this cohort. We recorded pain as worse, no change, improved, or resolved. This approach allowed the response of each patient to be compared with only his or her baseline pain, avoiding the direct comparison of VAS ratings among multiple patients who could assign different pain ratings to a given degree of pain.

Self-reported pain from patients with dementia typically was aided by the observation of close caregivers. It is generally thought that pain in patients with dementia is best assessed by self-report with supplemental information such as observations by caregivers when necessary, but the accuracy of self-assessment of pain alone is still questioned.^14,16 Studies have shown that relatives and caregivers can reasonably assess pain in patients with mild-to-moderate dementia.^14,17

Similarly, at each time point, mobility was reported as the percentage of patients reporting increased, unchanged, or decreased mobility, and medication use was reported as the percentage of patients with increased, unchanged, decreased, or no pain medication use.

Patient Population

From the initial screened cohort, 16 patients with known dementia were identified. Five of these were excluded due to the absence of confirming neuropsychologic testing or STMS, and 1 patient was excluded due to complete lack of follow-up. The 10 remaining patients consisted of 5 men and 5 women with an average age of 80 years (range, 65–90 years). There were 6 patients with a clinical diagnosis of Alzheimer disease, 1 with Lewy body dementia, 1 with “mixed” vascular and Alzheimer dementia, and 2 without a specific diagnosis. Eight patients had neuropsychologic testing, with a mean calculated DRS score of 106 (range, 71–133), 1 patient had a neuropsychologic test confirming dementia with no calculated DRS score, and 1 patient had a diagnosis of Alzheimer dementia with a STMS score of 23/38. A single patient had a DRS score of >130, but the overall results of the neuropsychologic testing were confirmatory of dementia.

All 10 patients had undergone lumbar vertebroplasty between February 2002 and October 2006. Eight patients had a single-level vertebroplasty, and 2 patients had 2-level vertebroplasty. The compression fractures resulted from osteoporosis in 8 patients, trauma in 1 patient, and a neoplasm in 1 patient. Four patients also had untreated fractures. The average time from the initial fracture was 2.0 ± 1.4 months. The average cement volume was 3.5 cm³. Conscious sedation was used in all patients. Nine patients used pain medication before the vertebroplasty. One patient did not initially use pain medication and remained free of medication throughout the study. Before the procedure, 4 patients were confined to a bed, 3 had restricted mobility, and 3 were ambulatory. Three patients died within the 1-year follow-up interval. One patient died 1 month postprocedure, and 2 patients, 1 year postprocedure.

Vertebroplasty Response

Most patients demonstrated decreased pain with rest and activity at all follow-up time points. Pain with activity decreased or resolved in 80%–100% of patients at each time point. Complete resolution of pain with activity was seen in 50% (3/6) of patients at 6 months, though this decreased to 25% (1/4) at 1 year. Similarly, pain at rest decreased or resolved in 78%–100% of all patients at each time point. Complete resolution of pain at rest was seen in 83% (5/6) of patients at 6 months, though this decreased to 50% (2/4) at 1 year. The pain with activity or at rest for all follow-up time points is summarized in Table 1.

Improved mobility was reported in 80%–100% of patients at all time points. Mobility was unchanged or worse in 20% (1/5) of patients at 1 month and in no patients at other time points. Pain medication was decreased or stopped in 67% (4/6) of patients at 1 week, 100% (6/6) of patients at 6 months, and 100% (3/3) at 1 year. The mobility and medication use are summarized in Table 2.