Standardised quantitative morphometry: a modified approach for quantitative identification of prevalent vertebral deformities

Corrigendum to how to define an osteoporotic vertebral fracture

[This corrects the article DOI: 10.21037/qims.2019.09.10.].

How to define an osteoporotic vertebral fracture?

A vertebral deformity (VD) is not always a vertebral fracture (VF). Because of lack of a completely satisfactory "gold standard", there is no consensus on the exact definition of a VF. Therefore, it may sometimes be difficult, especially in mild cases, to discriminate the prevalent VF from a non-fracture deformity or short vertebral height (SVH). A combined standardized approach based on qualitative and semiquantitative (SQ) vertebral assessment may be the most option to correctly identify a VD as a VF. However this visual approach for VF identification is subjective, therefore it is mandatory an adequate training and experience of radiologist to reach a good sensitivity and specificity. Vertebral morphometry, objective and reproducible method, could be used only to evaluate the severity of VFs but requires the availability of reference values of vertebral height ratios. There is actually an evidentiary basis for suggesting that a qualitative approach by expert radiologists to morphological vertebral assessment, combined SQ and morphometric methods seem to be the preferred option for the correct diagnosis of VF as endplate or/and cortex fracture (ECF) or severe vertebral height loss.

Impact of mild and moderate/severe vertebral fractures on physical activity: a prospective study of older women in the UK

Little is known about the long-term impact of vertebral fractures on physical activity. There is also uncertainty over the clinical significance of mild vertebral fracture. We showed that women with moderate/severe but not mild vertebral fracture do less walking duration and housework than those without fracture after 5.4 years of follow-up.

INTRODUCTION

Little is known about the long-term impact of vertebral fractures on physical activities. There is also uncertainty over the clinical significance of mild fracture. Therefore, the aim of this study was to evaluate the prospective association between vertebral fracture and future physical activity.

METHODS

This is a 5-year prospective study of a mixed community and secondary care cohort of women aged > 50 from the UK. Vertebral fractures were identified at baseline on radiographs or DXA-based Vertebral Fracture Assessment by a Quantitative Morphometric approach and defined as moderate/severe (≥ 25% height decrease) or mild (20-24.9% height decrease). Physical activity data were collected 5.4 years later by self-completion questionnaires. Multivariable logistic regression was used to determine the association between presence of fracture and various physical activities while adjusting for potential confounders.

RESULTS

Two hundred eighty-six women without, 58 with mild, and 69 with moderate/severe fracture were recruited. Those with mild and moderate/severe fracture were older than women without fracture and had more concomitant diseases at baseline. At 5.4 years follow-up, women with moderate/severe fracture self-reported shorter walking duration compared to those without fracture, even after adjusting for potential confounders (OR 2.96, 95%CI 1.11-7.88, P = 0.030). No independent association was seen between the presence of mild fractures and reduced physical activity at follow-up.

CONCLUSION

This is the first study of older women from the UK that explored the prospective association between vertebral fracture and physical activity duration. Moderate/severe fractures were associated with reduced walking duration. Mild fractures had no impact on future physical ability.

Vertebral Fractures: Clinical Importance and Management

Vertebral fractures are common and can result in acute and chronic pain, decreases in quality of life, and diminished lifespan. The identification of vertebral fractures is important because they are robust predictors of future fractures. The majority of vertebral fractures do not come to clinical attention. Numerous modalities exist for visualizing suspected vertebral fracture. Although differing definitions of vertebral fracture may present challenges in comparing data between different investigations, at least 1 in 5 men and women aged >50 years have one or more vertebral fractures. There is clinical guidance to target spine imaging to individuals with a high probability of vertebral fracture. Radiology reports of vertebral fracture need to clearly state that the patient has a "fracture," with further pertinent details such as the number, recency, and severity of vertebral fracture, each of which is associated with risk of future fractures. Patients with vertebral fracture should be considered for antifracture therapy. Physical and pharmacologic modalities of pain control and exercises or physiotherapy to maintain spinal movement and strength are important components in the care of vertebral fracture patients.

Vertebral Morphometry

There is as yet no agreement about the criteria by which to arrive at an imaging diagnosis of a vertebral fracture. Because high-grade fractures result in alterations in vertebral shape, 1 possible avenue of diagnosis has been to quantitate changes in vertebral shape. The result has been a variety of methods for the relative and absolute measurements of vertebral dimensions. Such measurements have also lent themselves to automated computed analysis. The number of techniques reflects the absence of any consensus about the best. The semiquantitative technique proposed by Genant has become the most widely used and has served the field well for comparative purposes. Its use in higher grade fractures has been widely endorsed, if some concepts (e.g., short vertebral height-vertebrae) are at variance with lower grades of fracturing. Vertebral morphometry may be the only recourse in high volume epidemiological and interventional studies.

Vertebral fracture assessment (VFA) by lateral DXA scanning may be cost-effective when used as part of fracture liaison services or primary care screening

SUMMARY

We identified that use of VFA may be cost-effective in either selected women from primary care or women attending after a low trauma fracture.

INTRODUCTION

Lateral DXA scanning of the spine for vertebral fracture assessment (VFA) is used for research, but its wider role is unclear. We aimed to establish whether VFA is cost-effective in women based on two different scenarios: following a low-trauma fracture, and after screening of high-risk women identified in primary care.

METHODS

The fracture cohort (FC) consisted of 377 women and the primary care cohort (PCC) of 251. Vertebral fractures were identified on VFA images by quantitative morphometry (QM). Outcome was cost-effectiveness of VFA, based on predicted change in clinical management defined as the identification of a vertebral fracture in a patient who otherwise falls below the threshold for treatment. FRAX treatment thresholds assessed were (1) 20/3 % thresholds and (2) National Osteoporosis Guidelines Group (NOGG) thresholds.

RESULTS

As a result, 9.8 % from FC and 13.9 % from PCC were identified with vertebral fractures. Management was changed in 21 to 22/377 (5.6-5.8 %) in FC and 12 to 26/251 (4.8-10.4 %) from PCC depending on which thresholds were used. Sensitivity analyses identified medication adherence as the assumption which most influenced the model. The best-estimate cost-per-QALY for use of VFA in FC was £3,243 for 20/3 threshold and £2,130 for NOGG; for PCC, this was £7,831 for 20/3 and was cost-saving for NOGG. Further analyses to adjust for potential false-positive vertebral fracture identification with QM showed VFA was no longer cost-effective.

CONCLUSION

VFA appears to be cost-effective in routine clinical practise, particularly when relatively inaccurate methods of identification of vertebral fractures are used such as QM.

Early diagnosis of vertebral fractures

Vertebral fractures are a common clinical entity, caused by trauma or related to osteoporosis (benign). Their recognition is especially important in the post-menopausal female population but also important is their differentiation from pathological (malignant) fractures (1). A vertebral fracture is evidenced by vertebral body deformity or reduction in vertebral body height beyond a certain threshold value in the absence of bone discontinuity. For prognosis and treatment it is extremely important to recognize the cause of the fracture. In contrast to fractures that occur in other locations, vertebral fractures often go unrecognized in the acute phase as the pain may be transient and radiographic and evaluation of the spine may be difficult (2). Objective measurement of the vertebral deformity provides invaluable information to the interpreting physician and helps grade fracture severity. The recognition and diagnosis of vertebral fractures can be performed using additional diagnostic tools.

Agreement between semi-automatic radiographic morphometry and Genant semi-quantitative method in the assessment of vertebral fractures

Semi-automatic morphometry is highly reproducible and not time intensive; however, no study has evaluated agreement between semi-automated morphometric methods and the Genant semi-quantitative method performed as a rule by radiologists. Our study shows substantial agreement between both methods; however, semi-automatic morphometry upgrades mild deformities and overestimates the prevalence of fractures.

INTRODUCTION

The aim of this study was to evaluate the agreement between radiologists using the Genant semi-quantitative (SQ) method and semi-automated morphometry in the diagnosis of vertebral fractures in post-menopausal women.

METHODS

Cross-sectional study was conducted in 2006-2007 in an age-stratified population-based sample of 824 post-menopausal women over the age of 50. From this population two sets of 95 and 50 X-ray were randomly extracted to test inter-rater agreement and agreement between SQ and semi-automated morphometry, and vertebral fractures were classified according to both methods. The Genant method was used to homogenise the diagnosis of fractures. Agreement was evaluated with weighted kappa. We evaluated each vertebral body independently and also the whole vertebral column (T4-L4) classifying women into the worst grade of fracture. For the qualitative interpretation of the agreement, we used the criteria described by Landis and Koch (Biometrics 33:159-174, 1977).

RESULTS

The radiologists' agreement was 98.4% (Kappa, 0.75; 95% CI, 0.42-0.89). Agreement between semi-automated morphometry and SQ reached 97.6% and Kappa was 0.86 (95% CI, 0.66-0.94). In the whole evaluation of the spine semi-automated morphometry overestimates, the prevalence of fractures compared with the radiologists were 15.8% of women with fractures and 7.4% of women with moderate-severe fractures by semi-automated morphometry vs. 8.4% and 3.2% by the SQ method. The negative predictive value for MorphoXpress was 99% while the positive was 40%.

CONCLUSIONS

Semi-automated morphometry shows high reliability and a substantial agreement with the SQ approach but overestimates the prevalence of fractures. Its role in routine clinical practice is limited because positive results should be reassessed by qualitative or semi-quantitative methods.

Vertebral morphometry

Visual semiquantitative (SQ) assessment of the radiographs by a trained and experienced observer is the "gold standard" method to detect vertebral fractures. Vertebral morphometry is a quantitative method to identify osteoporotic vertebral fractures based on the measurement of vertebral heights. Vertebral morphometry may be performed on conventional spinal radiographs (MRX: morphometric x-ray radiography) or on images obtained from dual x-ray absorptiometry (DXA) scans (MXA: morphometric x-ray absorptiometry). Vertebral fracture assessment (VFA) indicates the method for identification of the vertebral fractures using lateral spine views acquired by DXA, with low-dose exposition. For epidemiologic studies and clinical drug trials in osteoporosis research but also in clinical practice, the preferred method is radiographic SQ assessment., because an expert eye can better distinguish between true fractures and vertebral anomalies than can quantitative morphometry. However, vertebral morphometry, calculating the deformity of overall thoracic and lumbar spine, may supply useful data about the vertebral fracture risk. VFA performed during routine densitometry allows identification, by visual or morphometric methods, of most osteoporotic vertebral fractures, even those that are asymptomatic.

Vertebral fracture assessment: impact of instrument and reader

PURPOSE

Many osteoporotic vertebral fractures are not clinically recognized but increase fracture risk. We hypothesized that a newer generation densitometer increases the number of evaluable vertebrae and vertebral fractures detected. We also explored the impact of reader experience on vertebral fracture assessment (VFA) interpretation.

METHODS

VFA images obtained using Prodigy and iDXA densitometers in 103 older adults were evaluated for vertebral visualization and fracture presence in the T4-L5 region. A "true" read for each densitometer was achieved by consensus. If readers disagreed, the evaluation of a third expert physician was taken as true. Main outcomes were evaluable vertebrae, vertebral fractures, and intrareader/interreader reproducibility.

RESULTS

Using the "true" reads, 92% of vertebrae were visualized on iDXA and 76% on Prodigy. Numerically, more fractures were identified with iDXA; the "true" reads found 43 fractures on iDXA and 21 on Prodigy. The experienced reader had better intrareader and interreader reproducibility than the inexperienced reader when compared with the "true" read.

CONCLUSIONS

Using the newer iDXA densitometer for VFA analysis improves vertebral body visualization and fracture detection. Training and experience enhance result reproducibility.