Original ArticleImportance of Precision in Bone Density Measurements
Abstract
Bone densitometry, regardless of the specific technique, is not perfectly reproducible even when consistently performed in exact accordance with the manufacturer's recommendations. Precision must be quantified at each densitometry facility in precision studies of the various skeletal sites used for monitoring. The precision, as the root-mean-square standard deviation or root-mean-square coefficient of variation, is then used to determine the change in bone density that constitutes the least significant change and the minimum interval between follow-up measurements. Until precision studies are performed, the least significant change cannot be determined for any level of statistical confidence, making the interpretation of serial studies impossible.
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Assessment of Instrument Performance: Precision, Installation of New Equipment and Radiation Dose
- CC Glüer et al.
Accurate assessment of precision errors: how to measure the reproducibility of bone densitometry techniques
Osteoporos Int
(1995)
Cited by (244)
We assessed skeletal microstructure and stiffness in proton pump inhibitor (PPI) users compared to non-users with high resolution peripheral quantitative computed tomography (HRpQCT) and microfinite element analysis (μFEA) and other modalities. Relationships between PPI dose/frequency and bone parameters were evaluated.
We cross-sectionally assessed skeletal health in 601 older (≥age 65 years) adults (130 PPI users and 471 non-users) participating in a multi-ethnic population-based study of aging.
PPI users tended to have more comorbidities and take more medications than non-users. Female PPI users (n = 100) were more likely to be non-Caucasian, shorter with higher BMI, and more likely to have diabetes, lower physical activity and be using anti-depressants and thiazide diuretics compared to non-users (n = 302). Male PPI users (n = 30) were more likely to have liver disease than non-users (n = 169). In women, historical fractures (53.0 % vs. 43.4 %, p = 0.05) and falls (38 % vs. 26.8 %, p = 0.04) tended to be more frequent in PPI users compared to non-users. Number of falls was higher in women reporting daily rather than intermittent PPI use (1.8/year vs. 1.0/year, p < 0.001). In women, there were no differences in any HRpQCT or μFEA parameter. By HRpQCT, covariate-adjusted cortical volumetric bone density (Ct.vBMD) was 4.2 % lower in male PPI users vs. non-users at the tibia (p = 0.04), but this did not result in reduced stiffness. There were no other differences by HRpQCT at the tibia or radius.
PPI use was not associated with altered skeletal microstructure or stiffness in elderly men and women. The results do not support a relationship between PPI use and microstructure.
Thiazide diuretics, a commonly used class of anti-hypertensives, have been associated with increased areal bone mineral density (aBMD). Data regarding effects on fracture are conflicting and no information is available regarding effects on skeletal microstructure and mechanical competence.
We compared skeletal microstructure, volumetric BMD (vBMD), stiffness and prevalent fractures in current thiazide diuretic users and non-users from a population-based multiethnic cohort of elderly adults age ≥ 65 years (N = 599) with high resolution peripheral quantitative computed tomography (HR-pQCT) and micro-finite element analysis.
Female current thiazide diuretic users had higher weight and BMI and were more likely to be non-Caucasian compared to non-users. There were no differences in age, historical fractures or falls between female users and non-users. Female thiazide users tended to have lower calcium and vitamin d intake compared to non-users. After adjusting for age, weight, race and other covariates, 1/3-radius mean aBMD by dual energy x-ray absorptiometry (DXA) was 3.2% (p = 0.03) higher in female users vs. non-users. By HRpQCT, adjusted mean cortical vBMD was 2.4% (p = 0.03) higher at the radius in female users vs. non-users, but there was no difference in stiffness. DXA results were similar in the subset of Black females. There was no difference in any adjusted aBMD or cortical skeletal parameters by DXA or HRpQCT respectively in males.
Thiazide use was associated with a modestly higher aBMD at the predominantly cortical 1/3-radius site and radial cortical vBMD by HRpQCT in females. The effect on cortical bone may offer skeletal benefits in women taking thiazides for other indications such as hypertension, hypercalciuria or recurrent nephrolithiasis.
Assessing dynamic change in muscle during treatment of patients with cancer: Precision testing standards
2022, Clinical NutritionCitation Excerpt :Precision and the chosen confidence interval (CI) for precision error determines the LSC for skeletal muscle, which represents a statistically significant change in the patient's muscle and not simply owing to random errors in the measurements. The assessment of the precision error was carried out by referring to the ISCD recommendation [9,29]. The precision error was calculated as RMS SD of a set of measurements in cm2.
Computed tomography images acquired during routine cancer care provide an opportunity to determine body composition with accuracy and precision. Quantification of skeletal muscle is of interest owing to its association with clinical outcomes. However, the standards of precision testing considered mandatory in other areas of radiology are lacking from the literature in this area. We aim to describe the change in skeletal muscle over time at different anatomical levels using the precision error.
Thirty-eight male patients with squamous cell carcinoma of the head and neck were evaluated at two time points encompassing their treatment plan. Precision testing consisted of analyzing the cross-sectional area (CSA) of the skeletal muscle and total adipose tissue of 76 CT studies (38 images at baseline repeated twice and 38 follow-up images repeated twice) measured by a skilled observer. The % coefficient of variation (%CV), the root-mean-square standard deviation (RMS SD) and the corresponding 95% least significant change (LSC) were calculated for four anatomical levels: upper arm, thigh, chest and abdomen.
The median time between scans was 223.6 (SD 31.2) days. Precision error (% CV) for total skeletal muscle cross sectional area was 0.86% for upper arm, 0.26% for thigh, 0.39% for chest and 0.63% for abdomen. The corresponding LSC values in upper arm, thigh, chest and abdomen were 2.4%, 0.7%, 1.1% and 1.8%, respectively.
Based on the LSC for RMS SD, patients were classified in two categories according to muscle cross-sectional area: stable (i.e within LSC value) or gained and loss. To compare the four anatomical levels, the proportion of patients with muscle loss exceeding the LSC value was 74.3% for arm, 86.2% for thigh, 82.9% for chest and 76.3% for abdomen. For these same anatomic regions, the mean muscle loss for those patients classified below the LSC was 14.6% (SD 9.3), 13.4% (SD 7.8), 11.9% (SD 6.5) and 11.6% (SD 5.5), respectively. Only the loss of muscle area was significantly higher in thigh (p = 0.023), using L3 as the reference level.
We recommend the uniform use of a standard precision test when reporting muscle change over time. LSC values vary from 0.7 to 2.4% depending on anatomic site; with the lowest precision error to detect change in the thigh.
Based on this analysis, muscle wasting appears to be systemic and while present in limbs and trunk is significantly higher in the thigh than in the chest, abdomen or upper arm.
Smoking Is Associated with Sex-Specific Effects on Bone Microstructure in Older Men and Women
2021, Journal of Clinical DensitometryBackground: Smoking is a risk factor for fracture, but the mechanism by which smoking increases fracture risk is unclear. Methods: Musculoskeletal health was compared with dual energy X-ray absorptiometry (DXA), high resolution peripheral quantitative computed tomography (HR-pQCT), trabecular bone score, and vertebral fracture assessment in current and past smokers and nonsmokers from a multiethnic study of adults ≥ age 65. Skeletal indices were adjusted for age and weight. Results: Participants (n = 311) were mean age (±SD) 76.1 ± 6.5 years, mostly female (66.0%) and non-white (32.7% black/39.4% mixed race/26.3% white). Mean pack-years was 34.6 ± 20.4. In men (n = 106), weight and BMI were lower (both p < 0.05) in current vs past smokers. Male smokers consumed half the calcium of never and past smokers. BMD by DXA did not differ by smoking status at any skeletal site in either sex. Current male smokers had 13.5%–15.3% lower trabecular bone score vs never and past smokers (both p < 0.05). By HR-pQCT, trabecular volumetric BMD was 26.6%–30.3% lower and trabeculae were fewer, thinner and more widely spaced in male current vs past and never smokers at the radius (all p < 0.05). Cortical indices did not differ. Tibial results were similar, but stiffness was also 17.5%–22.2% lower in male current vs past and never smokers (both p< 0.05). In women, HR-pQCT trabecular indices did not differ, but cortical porosity was almost twice as high in current vs never smokers at the radius and 50% higher at the tibia (both p < 0.05). Conclusions: In summary, current smoking is associated with trabecular deterioration at the spine and peripheral skeleton in men, while women have cortical deficits. Smoking may have sex-specific skeletal effects. The consistent association with current, but not past smoking, suggests the effects of tobacco use may be reversible with smoking cessation.
Bone Mineral Density (BMD) improves after parathyroidectomy (PTX), but data on factors that predict bone recovery are limited. No studies have evaluated if preoperative imaging findings are associated with postoperative change in BMD. We hypothesized that larger, metabolically active glands would be associated with greater increase in BMD after PTX.
Patients with primary hyperparathyroidism (PHPT) who underwent combined Tc-99m sestamibi and 4D-CT imaging prior to PTX and had pre- and post-operative dual-energy X-ray absorptiometry (DXA) at our institution were considered for inclusion. Retrospectively, data were collected from imaging studies on each parathyroid gland, including estimated weight (using the ellipsoid formula) and contrast enhancement on 4D-CT as well as sestamibi avidity. Total estimated parathyroid weight was calculated. The main outcome measure was the percent change in BMD at the lumbar spine (LS) from pre- to post-operative DXA. Predictors of change in BMD at the LS were assessed.
Complete DXA data was available in 25 patients. Median total parathyroid weight on 4D-CT was 270 mg, and mean change in BMD at the LS was 2.4 ± 4.3%. The increase in BMD was best predicted by higher preoperative serum calcium (p = 0.01), greater estimated parathyroid weight (p = 0.001), sestamibi avidity (p = 0.03), and increased time between DXA scans (p = 0.03) in the multivariable model (R2 = 0.79, p < 0.0001).
In PHPT, higher preoperative serum calcium, parathyroid gland weight on imaging, and sestamibi avidity are associated with greater increases in BMD after curative PTX. These findings suggest that larger, metabolically active adenomas may mobilize more calcium from bone.
Anti-depressants, particularly selective serotonin reuptake inhibitors (SSRIs), are associated with an increased risk of fracture. The mechanism is unclear and may be due to effects on bone metabolism, muscle strength, falls or other factors. It is unknown if serotonin norepinephrine reuptake inhibitors (SNRIs) have similar effects.
We compared musculoskeletal health in current female anti-depressant users and non-users from a population-based multiethnic (35.6% black, 22.3% white and 42.1% mixed) cohort study of adults ≥65 years old in New York (N = 195) using dual x-ray absorptiometry (DXA), trabecular bone score (TBS), vertebral fracture assessment (VFA), high resolution peripheral quantitative computed tomography (HR-pQCT), body composition, and grip strength.
Current anti-depressant users were more likely to be white than non-white (OR 1.9, 95% CI 1.2–2.9) and were shorter than non-users, but there were no differences in age, weight, BMI, physical activity, calcium/vitamin D intake, falls or self-rated health. There were more pelvic fractures in current vs. non-users (7.1% vs. 0%, p = 0.04). Age- and weight-adjusted T-score by DXA was lower in current users at the 1/3-radius (−1.6 ± 1.1 vs. −1.0 ± 1.4, p = 0.04) site only. There was no difference in TBS, vertebral fractures or fat/lean mass by DXA. Age- and weight-adjusted grip strength was 13.3% lower in current users vs. non-users (p = 0.04). By HR-pQCT, age- and weight-adjusted cortical volumetric BMD (Ct. vBMD) was 4.8% lower in users vs. non-users at the 4% radius site (p = 0.007). A similar cortical pattern was seen at the proximal (30%) tibia. When assessed by anti-depressant class, deteriorated cortical microstructure was present only in SSRI users at the radius and only in SNRI users at the proximal tibia.
Anti-depressant use is associated with cortical deterioration and reduced physical function, but effects may be class-specific. These findings provide insight into the mechanism by which anti-depressants may contribute to the increased fracture risk in older women.