Machine learning models with time-series clinical features to predict radiographic progression in patients with ankylosing spondylitis

Objective

Ankylosing spondylitis (AS) is chronic inflammatory arthritis causing structural damage and radiographic progression to the spine due to repeated and continuous inflammation over a long period. This study establishes the application of machine learning models to predict radiographic progression in AS patients using time-series data from electronic medical records (EMRs).

Methods

EMR data, including baseline characteristics, laboratory findings, drug administration, and modified Stoke AS Spine Score (mSASSS), were collected from 1,123 AS patients between January 2001 and December 2018 at a single center at the time of first (T1), second (T2), and third (T3) visits. The radiographic progression of the (n+1)th visit (Pn+1=(mSASSSn+1-mSASSSn)/(Tn+1-Tn)≥1 unit per year) was predicted using follow-up visit datasets from T1 to Tn. We used three machine learning methods (logistic regression with the least absolute shrinkage and selection operation, random forest, and extreme gradient boosting algorithms) with three-fold cross-validation.

Results

The random forest model using the T1 EMR dataset best predicted the radiographic progression P2 among the machine learning models tested with a mean accuracy and area under the curves of 73.73% and 0.79, respectively. Among the T1 variables, the most important variables for predicting radiographic progression were in the order of total mSASSS, age, and alkaline phosphatase.

Conclusion

Prognosis predictive models using time-series data showed reasonable performance with clinical features of the first visit dataset when predicting radiographic progression.

Radiographic involvement of cervical facet joints in ankylosing spondylitis: a longitudinal analysis in correlation with vertebral body lesions

BACKGROUND

The inability to assess structural changes in facet joints is a limitation of established radiographic scoring systems for ankylosing spondylitis (AS). We compared radiographic evidence of ankylosis in cervical facet joints and cervical vertebral bodies in patients with AS.

METHODS

We analysed longitudinal data collected from 1106 AS patients and assessed 4984 spinal radiographs obtained up to 16 years of follow-up. Comparisons between cervical facet joints and cervical vertebral bodies focused on the presence of ankylosis, which was defined by at least one facet joint exhibiting complete ankylosis (according to the method of de Vlam) or at least one vertebral body with a bridging syndesmophyte (according to the modified Stoke Ankylosing Spondylitis Spinal Score [mSASSS]). Ankylosis was assessed over time using spinal radiographs collected during follow-up periods stratified in 4-year increments.

RESULTS

Patients with cervical facet joint ankylosis had higher cervical mSASSS, sacroiliitis grades, and inflammatory markers, with more prevalent hip involvement and uveitis. Overall, the numbers of spinal radiographs indicating ankylosis were comparable between cervical facet joints (17.8%) and cervical vertebral bodies (16.8%), and they usually presented together (13.5%). We observed similar proportions of radiographs with ankylosis only in cervical facet joints (4.3%) and cervical vertebral bodies (3.3%). As damage progressed, configurations with both cervical facet joint ankylosis and bridging syndesmophytes became more predominant with longer follow-up times, while configurations with cervical facet joint ankylosis only or bridging syndesmophytes only were less frequently observed.

CONCLUSIONS

Evidence of cervical facet joint ankylosis appears as often as bridging syndesmophytes on routine AS spinal radiographs. Presence of cervical facet joint ankylosis should be considered because it may have a higher disease burden.

Association between changes in serum alkaline phosphatase levels and radiographic progression in ankylosing spondylitis

This retrospective study evaluated the electronic medical records of patients with ankylosing spondylitis (AS) (January 2001-December 2018) to determine the relationship between serum alkaline phosphatase (ALP) levels and radiographic changes over time. Longitudinal data, including serum ALP levels, were imputed by linear interpolation at 3-month intervals. Among the serum ALP levels calculated for 8 years prior to modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) measurement, those having the highest beta coefficient with the mSASSS were selected in the correlation between ALP and longitudinal mSASSS. Linear mixed models with the selected serum ALP levels, mSASSS, and clinical variables were investigated. We included 1122 patients (mean follow-up, 8.20 [standard deviation: 2.85] years). The serum ALP level from 5 years and 3 months prior showed the highest beta coefficient with the mSASSS. In the linear mixed model, the serum ALP level at 5 years and 3 months before radiographic changes was significantly associated with the mSASSS (β = 0.021, 95% confidence interval: 0.017-0.025, p < 0.001). Serum ALP levels measured approximately 5 years before may be a surrogate marker for predicting spinal radiographic changes. Long-term prospective clinical and experimental studies of > 5 years are required for biomarker discovery or therapeutic research on AS radiographic progression.

Clinical and genetic factors associated with radiographic damage in patients with ankylosing spondylitis

OBJECTIVES

To identify clinical and genetic factors associated with severe radiographic damage in patients with ankylosing spondylitis (AS).

METHODS

We newly generated genome-wide single nucleotide polymorphism data (833K) for 444 patients with AS. The severity of radiographic damage was assessed using the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). To identify clinical and genetic factors associated with severe radiographic damage, multiple linear regression analyses were performed. Human AS-osteoprogenitor and control-osteoprogenitor cells were used for functional validation.

RESULTS

The significant clinical factors of final mSASSS were baseline mSASSS (β=0.796, p=3.22×10-75), peripheral joint arthritis (β=-0.246, p=6.85×10-6), uveitis (β=0.157, p=1.95×10-3), and smoking (β=0.130, p=2.72×10-2) after adjusting for sex, age and disease duration. After adjusting significant clinical factors, the Ryanodine receptor 3 (RYR3) gene was associated with severe radiographic damage (p=1.00×10-6). For pathway analysis, the PI3K-Akt signalling pathway was associated with severe radiographic damage in AS (p=2.21×10-4, false discovery rate=0.040). Treatment with rhodamine B, a ligand of RYR3, dose-dependently induced matrix mineralisation of AS osteoprogenitors. However, the rhodamine B-induced accelerated matrix mineralisation was not definitive in control osteoprogenitors. Knockdown of RYR3 inhibited matrix mineralisation in SaOS2 cell lines.

CONCLUSIONS

This study identified clinical and genetic factors that contributed to better understanding of the pathogenesis and biology associated with radiographic damage in AS.

Relationship Between Inflammation and Radiographic Progression in Patients With Ankylosing Spondylitis Attaining a BASDAI of Less Than 4 During Tumor Necrosis Factor Inhibitor Treatment

OBJECTIVE

To determine the relationship between inflammation and radiographic progression over time in patients with ankylosing spondylitis (AS) attaining a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) of < 4 during tumor necrosis factor inhibitor (TNFi) treatment.

METHODS

Medical records data of patients with AS with BASDAI scores of < 4 during TNFi treatment were analyzed at 6-month intervals from January 2001 to December 2018. To determine the relationship between the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) and C-reactive protein (CRP) over time, we fitted linear mixed models with mSASSS as the response variable, baseline mSASSS and the cumulative sum of CRP with different lag times (6, 12, 18, 24, 30, and 36 months) as fixed effects, and patients as random effects. Associations between mSASSS and the cumulative sum of CRP, or the lag times with the highest beta coefficients, were further investigated with linear mixed models that included additional clinical variables.

RESULTS

A total of 2956 intervals were obtained from 333 patients. Among different lag times, the cumulative sum of log CRP in the previous 18 to 36 months associated with mSASSS showed significant beta coefficients. In the final linear mixed model, the cumulative sum of log CRP in the previous 24 months was significantly associated with mSASSS at 24 months (β 0.04, 95% CI 0.01-0.07, P = 0.004).

CONCLUSION

Remnant inflammation correlates with radiographic progression, even in patients attaining a BASDAI of < 4 during TNFi treatment. CRP is a surrogate marker for radiographic progression despite clinical improvement with TNFi treatment.

The impact of smoking status on radiographic progression in patients with ankylosing spondylitis on anti-tumor necrosis factor treatment

Background

Ankylosing spondylitis (AS) is characterized by back pain which can lead to spinal ankylosis. Anti-tumor necrosis factor (TNF) dramatically alleviates symptoms, but spinal damage can still be progressive even during anti-TNF treatment. Smoking is a one of well-known risk factors for structural damage in AS. However, it has not been confirmed that smoking can affect radiographic progression even during anti-TNF treatment.

Objective

To investigate factors associated with radiographic progression during anti-TNF treatment with a focus on smoking status which is known as one of poor prognostic factors for AS.

Materials and methods

We conducted a retrospective cohort study of AS patients who began the first-line anti-TNF treatment between 2001 and 2018 according to availability of smoking data. All enrolled patients were observed until the last visit, the first-line anti-TNF discontinuation, or December 2019. Radiographic damage was assessed using the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). The mSASSS progression rate (units/year) was calculated using the baseline mSASSS, the final mSASSS during observation period, and the duration between them. Univariable and multivariable logistic regression analyses were performed to identify associated factors of mSASSS progression rate > 1 unit/year.

Results

Among 459 AS patients, 185 (40.3%) patients were never smokers, 62 (13.5%) were ex-smokers and 212 (46.2%) were current smokers at baseline. Ex- and current smokers had higher mSASSS progression rates than never smokers [never smoker 0.1 (0.0–0.7), ex-smoker 0.6 (0.0–1.5), and current smoker 0.6 (0.0–1.5) units/year, P < 0.001]. In the multivariable logistic analysis, current smoking [adjusted odds ratio (OR) 1.69, 95% CI 1.01–2.82, P = 0.047] and higher baseline mSASSS [adjusted OR 1.03, 95% CI 1.01–1.04, P < 0.001] were associated with a mSASSS progression rate > 1 unit/year.

Conclusion

Current smoking is a modifiable risk factor for radiographic progression in patients with AS on anti-TNF treatment. Quitting smoking should be strongly recommended.

A pilot study on deep learning-based grading of corners of vertebral bodies for assessment of radiographic progression in patients with ankylosing spondylitis

Background:

Radiographs are widely used to evaluate radiographic progression with modified stoke ankylosing spondylitis spinal score (mSASSS).

Objective:

This pilot study aimed to develop a deep learning model for grading the corners of the cervical and lumbar vertebral bodies for computer-aided detection of mSASSS in patients with ankylosing spondylitis (AS).

Methods:

Digital radiographic examination of the spine was performed using Discovery XR656 (GE Healthcare) and Digital Diagnost (Philips). The disk points were detected between the bodies using a key-point detection deep learning model from the image obtained in DICOM (digital imaging and communications in medicine) format from the cervical and lumbar spinal radiographs. After cropping the vertebral regions around the disk point, the lower and upper corners of the vertebral bodies were classified as grade 3 (total bony bridges) or grades 0, 1, or 2 (non-bridges). We trained a convolutional neural network model to predict the grades in the lower and upper corners of the vertebral bodies. The performance of the model was evaluated in a validation set, which was separate from the training set.

Results:

Among 1280 patients with AS for whom mSASSS data were available, 5,083 cervical and 5245 lumbar lateral radiographs were reviewed. The total number of corners where mSASSS was measured in the cervical and lumbar vertebrae, including the upper and lower corners, was 119,414. Among them, the number of corners in the training and validation sets was 110,088 and 9326, respectively. The mean accuracy, sensitivity, and specificity for mSASSS scoring in one corner of the vertebral body were 0.91604, 0.80288, and 0.94244, respectively.

Conclusion:

A high-performance deep learning model for grading the corners of the vertebral bodies was developed for the first time. This model must be improved and further validated to develop a computer-aided tool for assessing mSASSS in the future.

Age-stratified trends in the progression of spinal radiographic damage in patients with ankylosing spondylitis: a longitudinal study

Objective:

The objective of this study was to investigate spinal radiographic progression in specific age ranges of ankylosing spondylitis (AS) patients.

Methods:

Longitudinal data for 1125 AS patients at a single hospital from 2000 to 2018 were retrospectively reviewed. Radiographic intervals were obtained from patients with consecutive spinal radiographs. The radiographic progression rate was defined as the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) change per year within each interval. Using generalized estimating equations (GEEs), estimated marginal means were calculated for the mSASSS progression rate across age groups after adjusting for potential confounders.

Results:

We obtained 4016 radiographic intervals and stratified them into five groups based on patient age at the interval start: <20 (n = 122); 20–29 (n = 1124); 30–39 (n = 1690); 40–49 (n = 794); and ⩾50 years (n = 286). The mean (SD) mSASSS progression rate for all the intervals was 0.8 (1.9). The GEE-estimated mean mSASSS progression rate increased with age, peaking in the 30–39 age group with a value of 1.15 [95% confidence interval (CI) 1.03, 1.27], and decreased slightly thereafter. In the presence of risk factors, rapid progression occurred at earlier ages: the GEE-estimated mean mSASSS progression rate in those with elevated C-reactive protein levels and preexisting syndesmophytes was 2.82 (95% CI 1.93, 3.71) in the 20–29 age group.

Conclusion:

Spinal structural damage in AS seems to progress most rapidly when patients are age 30–39 years. An awareness of the trends in radiographic progression with advancing age could improve understanding of the natural course of AS.

Early control of C-reactive protein levels with non-biologics is associated with slow radiographic progression in radiographic axial spondyloarthritis

AIM

Predicting radiographic progression is vital for assessing the prognosis of patients with radiographic axial spondyloarthritis, and C-reactive protein (CRP) may be a valuable biomarker for this purpose. This study aimed to investigate the relationship between changes in the CRP level and spinal radiographic progression in patients with radiographic axial spondyloarthritis who were initially treated with non-biologics.

METHODS

Patients with radiographic axial spondyloarthritis who were followed up for 18 years at a single center and initially treated with nonsteroidal anti-inflammatory drugs and/or conventional disease-modifying antirheumatic drugs for 3 months were included. Patients with a CRP level of <0.8 mg/dL or 50% of the baseline CRP at 3 months were assigned to the controlled CRP group (n = 351), and the remaining patients were assigned to the uncontrolled CRP group (n = 452). A generalized estimating equation was used to analyze the differences in the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) between the 2 groups.

RESULTS

The increase in the mSASSS was slower in the controlled CRP group than in the uncontrolled CRP group (interaction term β = -.499, 95% confidence interval -0.699 to -0.300).

CONCLUSION

Controlled CRP achieved in response to initial treatment with non-biologic agents for 3 months was significantly associated with a slower rate of spinal radiographic change in patients with radiographic axial spondyloarthritis. The CRP level at 3 months after initial non-biologic treatment is a good predictor of radiographic progression.

Use of Quantitative Vertebral Bone Marrow Fat Fraction to Assess Disease Activity and Chronicity in Patients with Ankylosing Spondylitis

Objective

We quantitatively measured the fat fraction (FF) in the vertebrae of patients with ankylosing spondylitis (AS) using magnetic resonance imaging (MRI) and investigated the role of FF as an indicator of both active inflammation and chronicity.

Materials and Methods

A total of 52 patients with AS who underwent spinal MRI were retrospectively evaluated. The FF values of the anterosuperior and anteroinferior corners of the bone marrow in the L1-S1 spine were assessed using the modified Dixon technique. AS activity was measured using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), AS Disease Activity Score (ASDAS), and serum inflammatory marker levels. AS disease chronicity was assessed by AS disease duration and the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). Univariable and multivariable regression analyses were conducted to investigate the correlation between FF and other clinical characteristics.

Results

The mean FF ± standard deviation of the total lumbar spine was 43.0% ± 11.3%. At univariable analysis, spinal FF showed significant negative correlation with BASDAI (β = −0.474, p = 0.002) and ASDAS with C-reactive protein (ASDAS-CRP; β = −0.478, p = 0.002) and a significant positive correlation with AS disease duration (β = 0.440, p = 0.001). After adjusting for patient age, sex, and total mSASSS score, spinal FF remained significantly negatively correlated with BASDAI (β = −0.543, p < 0.001), ASDAS-CRP (β = −0.568, p < 0.001), and ASDAS with erythrocyte sedimentation rate (β = −0.533, p = 0.001). Spinal FF was significantly lower in patients with very high disease activity (ASDAS-CRP > 3.5) than in those with only high disease activity (2.1 ≤ ASDAS-CRP ≤ 3.5) (p = 0.010).

Conclusion

Spinal FF may help assess both AS disease activity and chronicity.

Low BASDAI score alone is not a good predictor of anti-tumor necrosis factor treatment efficacy in ankylosing spondylitis: a retrospective cohort study

Background

The purpose of this study was to determine the prevalence of high disease activity as measured using the Ankylosing Spondylitis Disease Activity Score (ASDAS) in ankylosing spondylitis (AS) patients who nonetheless have low Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores after anti-tumor necrosis factor (TNF) treatment. Its clinical impact on anti-TNF survival was also investigated.

Methods

We conducted a single-centre retrospective cohort study of AS patients having low BASDAI scores (< 4) and available ASDAS-C-reactive protein (CRP) data after 3 months of first-line anti-TNF treatment. Patients were grouped into high-ASDAS (≥ 2.1) and low-ASDAS (< 2.1) groups according to the ASDAS-CRP after 3 months of anti-TNF treatment. Their characteristics were compared. And survival analyses were carried out using Kaplan–Meier curves and log-rank test with the event being discontinuation of anti-TNF treatment due to lack/loss of efficacy.

Results

Among 116 AS patients with low BASDAI scores after 3 months of anti-TNF treatment, 38.8% were grouped into the high-ASDAS group. The high-ASDAS group tended to have greater disease activity after 9 months of treatment (BASDAI 2.9 ± 1.1 vs. 2.3 ± 1.4, p=0.007; ASDAS-CRP 1.8 ± 0.6 vs. 1.5 ± 0.7, p=0.079; proportion of high ASDAS-CRP 27.8% vs. 13.8%, p=0.094) and greater risk of discontinuing anti-TNF treatment due to lack/loss of efficacy than the low-ASDAS group (p=0.011).

Conclusions

A relatively high proportion of AS patients with low BASDAI scores had high ASDAS-CRP. These low-BASDAI/high-ASDAS-CRP patients also had a greater risk for discontinuation of anti-TNF treatment due to low/lack of efficacy than the low-ASDAS group. The use of the ASDAS-CRP alone or in addition to the BASDAI may improve the assessment of AS patients treated with anti-TNF agents.

Conventional disease-modifying antirheumatic drugs therapy may not slow spinal radiographic progression in ankylosing spondylitis: results from an 18-year longitudinal dataset

Objectives:

The clinical benefit of conventional disease-modifying antirheumatic drugs (cDMARDs) for treating ankylosing spondylitis (AS) is generally limited to improvements in peripheral arthritis. However, cDMARDs could be conditionally considered as alternatives to established drugs for improving axial manifestations in exceptional circumstances. However, there are few studies of the impact of cDMARDs on radiographic progression outcomes. Therefore, we investigated the effectiveness of cDMARDs on radiographic progression in AS.

Methods:

Among 1280 AS patients at a single hospital from 2000 to 2018, 301 who had been treated with sulfasalazine (SSZ) or methotrexate (MTX) were enrolled. For each patient, the entire follow-up period was split into 1-year intervals. Each interval was classified as either an “on-cDMARD” interval, which was a period of treatment with SSZ alone, MTX alone, or a combination of SSZ and MTX, or an “off-cDMARD” interval, which was a period without cDMARD treatment. Radiographic progression was scored using the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). The relationship between cDMARD use and radiographic progression within the intervals, defined as the rate of mSASSS progression, was investigated using linear models with adjustment for potential confounding covariates and for clustering among observations from the same patient.

Results:

The 732 on-cDMARD intervals and 1027 off-cDMARD intervals were obtained from enrolled patients. In multivariable regression analysis, there was no significant association between cDMARDs and the rate of mSASSS progression (β = −0.081, p = 0.418). The mean adjusted mSASSS change per year was 0.610 from on-cDMARD intervals and 0.691 from off-cDMARD intervals.

Conclusion:

Treatment with cDMARDs may not reduce radiographic progression in AS patients.

Tumour necrosis factor inhibitors slow radiographic progression in patients with ankylosing spondylitis: 18-year real-world evidence

OBJECTIVES

Tumour necrosis factor inhibitors (TNFis) have been suggested to slow radiographic progression in patients with ankylosing spondylitis. However, limitations such as variations in disease activity, complex drug administration and short follow-up duration make it difficult to determine the effect of TNFis on radiographic progression. The aim of the study was to investigate whether long-term treatment with TNFis can reduce radiographic progression in patients with ankylosing spondylitis using 18-year longitudinal real-world data.

METHODS

This retrospective study was conducted between January 2001 and December 2018 at a single centre. Among the 1280 patients whose electronic medical records were reviewed, data of 595 patients exposed to TNFis at least once were included. Among them, time intervals of TNFi exposure or non-exposure were determined in 338 patients ('on the TNFis' or 'off the TNFis' intervals, respectively). The difference in the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) change rate between 'on the TNFis' and 'off the TNFis' intervals was investigated.

RESULTS

We obtained 2364 intervals of 338 patients (1281 'on the TNFis' and 1083 'off the TNFis' intervals). In the marginal structural model for inverse probability of treatment weighting, the change rate of mSASSS significantly decreased with the use of TNFis (β=-0.112, p=0.004), and the adjusted mSASSS changes were 0.848 and 0.960 per year during 'on the TNFis' and 'off the TNFis' intervals, respectively.

CONCLUSION

Compared with treatment without TNFis, treatment with TNFis slowed radiologic progression significantly.

Radiologic Changes in the Symphysis Pubis of Male Patients with Ankylosing Spondylitis

OBJECTIVE

We aimed to evaluate the involvement of the symphysis pubis in patients with ankylosing spondylitis (AS), and to assess the correlations between symphysis pubis changes and clinical findings.

METHODS

We retrospectively evaluated a total of 222 male patients with AS who underwent pelvic and cervical/lumbar spine radiography at the Hanyang University Hospital for Rheumatic Diseases from August 2004 to February 2014. Radiographs were examined by 2 experienced radiologists, and radiographic damage was scored as follows: 0 (no damage), 1 (subtle irregularity and/or subchondral sclerosis), 2 (erosion), 3 (partial ankylosis), and 4 (total ankylosis). We evaluated the patients' clinical characteristics and analyzed their correlations with radiographic symphysis pubis changes.

RESULTS

The mean patient age was 30.5 ± 8.3 years and mean disease duration was 7.1 ± 4.6 years; 105 patients (47.3%) exhibited radiologic damage in the symphysis pubis. Moreover, 75, 28, 0, and 2 patients had scores of 1, 2, 3, and 4, respectively. When comparing the normal (score 0) and abnormal (score 1-4) symphysis pubis groups, the latter had a longer symptom duration (10.1 ± 7.0 vs 7.6 ± 5.8 yrs, p = 0.004) and higher modified Stoke Ankylosing Spondylitis Spine Score (mSASSS; 18.6 ± 17.0 vs. 14.3 ± 13.4, p = 0.038). Moreover, a significant correlation was noted between the radiographic symphysis pubis damage score and mSASSS (r(2) = 0.147, p = 0.029).

CONCLUSION

Among male patients with AS, 47.3% exhibited symphysis pubis involvement. Moreover, a correlation was observed between the radiographic symphysis pubis and spine changes.

Loss of anterior concavity of the first sacrum can predict spinal involvement in ankylosing spondylitis

In this study, we evaluated the frequency of squaring of the first sacrum (S1), defined as the loss of anterior concavity, in patients with ankylosing spondylitis (AS). We also determined the interobserver reliability in the assessment of S1 squaring and the relationships of S1 squaring with MRI findings and the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). To this end, we performed a retrospective study of 100 patients with AS (mean age 33.2 years; range 19-57 years) and 100 control patients (mean age 35.6 years; range 19-50 years). Four experienced radiologists independently assessed the presence of S1 squaring in the AS and control groups. The frequencies of S1 squaring as scored by the four observers were 47, 48, 46, and 42 in the AS group and 3, 6, 4, and 6 in the control group. The interobserver agreement among the four observers with respect to S1 squaring was excellent (κ value 0.80) in the AS group and fair to good (κ value 0.61) in the control group. In patients with AS, the presence of S1 squaring showed fair to good agreement with the MRI changes (κ value 0.74). Moreover, the mSASSSs of patients with versus without S1 squaring were significantly different (mean 23.9 vs 7.0, p < 0.001). In conclusion, S1 squaring is relatively common in patients with AS. Moreover, S1 squaring is closely correlated with MRI changes and significantly associated with the mSASSS. Assessment of S1 squaring could be a simple method that is potentially useful for predicting early spinal structural involvement in patients with AS.

Bone morphogenetic protein 6 polymorphisms are associated with radiographic progression in ankylosing spondylitis

BACKGROUND AND OBJECT

Nearly 25 genetic loci associated with susceptibility to ankylosing spondylitis (AS) have been identified by several large studies. However, there have been limited studies to identify the genes associated with radiographic severity of the disease. Thus we investigated which genes involved in bone formation pathways might be associated with radiographic severity in AS.

METHODS

A total of 417 Korean AS patients were classified into two groups based on the radiographic severity as defined by the modified Stoke' Ankylosing Spondylitis Spinal Score (mSASSS) system. Severe AS was defined by the presence of syndesmophytes and/or fusion in the lumbar or cervical spine (n = 195). Mild AS was defined by the absence of any syndesmophyte or fusion (n = 170). A total of 251 single nucleotide polymorphisms (SNPs) within 52 genes related to bone formation were selected and genotyped. Odds ratios (OR) and 95% confidence interval (95% CI) were analysed by multivariate logistic regression controlling for age at onset of symptoms, sex, disease duration, and smoking status as covariates.

RESULTS

We identified new loci of bone morphogenetic protein 6 (BMP6) associated with radiographic severity in patients with AS that passed false discovery rate threshold. Two SNPs in BMP6 were significantly associated with radiologic severity [rs270378 (OR 1.97, p = 6.74 × 10(-4)) and rs1235192 [OR 1.92, p = 1.17 × 10(-3)]) adjusted by covariates.

CONCLUSION

This is the first study to demonstrate that BMP6 is associated with radiographic severity in AS, supporting the role wingless-type like/BMP pathway on radiographic progression in AS.

The presence of peripheral arthritis delays spinal radiographic progression in ankylosing spondylitis: Observation Study of the Korean Spondyloarthropathy Registry

OBJECTIVES

The aim of this study was to determine whether the presence of peripheral arthritis can affect radiographic structural damage in patients with AS.

METHODS

A total of 915 subjects comprising 363 patients with a history of peripheral arthritis and 552 patients without a history of peripheral arthritis obtained from the Observation Study of the Korean SpA Registry (OSKAR) were analysed looking at the relationship of peripheral arthritis history in a cross-sectional survey as well as the radiographic damage score according to the presence or absence of peripheral arthritis. Radiographs and clinical information were available for 501 subjects (205 peripheral arthritis patients and 296 without peripheral arthritis) at a mean follow-up of 2.7 years. The modified Stoke AS Spinal Score (mSASSS) was examined by two experienced radiologists to validate the results. Reliability was evaluated using the intraclass correlation coefficient for each radiograph.

RESULTS

The agreement between the two readers regarding the mSASSS was good. On simple comparison there was a significant difference in the mSASSS between patients with a history of peripheral arthritis and those without [mean 14.62 (s.e.m. 0.83) vs 18.78 (0.79), P < 0.001]. The mSASSS change was stratified according to the presence or absence of peripheral arthritis at baseline. After adjusting for multiple comparisons by Bonferroni correction, the patients with peripheral arthritis had less mSASSS change than those without peripheral arthritis [3.08 (s.e.m. 0.61) vs 5.18 (0.47), P = 0.008].

CONCLUSION

The presence of peripheral arthritis delays spinal radiographic progression in AS.

Growing heterotopic calcification in the prevertebral space of a cervical spine as a late complication of irradiation: case report

Heterotopic calcification following head and neck irradiation has rarely been reported. It usually develops as a late complication of radiotherapy in patients with malignancies, including breast cancer, lymphoma, and genitourinary malignancies. The occurrence of heterotopic calcification in the prevertebral space of the cervical spine has not been described as a late complication of irradiation. Here, we report a case of prevertebral heterotopic calcification in a patient with history of chemotherapy and radiotherapy for tonsil cancer 21 years ago.

Intraarticular osteochondroma of shoulder: a case report

Osteochondroma is a cartilage-capped osseous protrusion that arises from the surface of a bone. Osteochondroma occurs mostly in the metaphysis of long tubular bones such as the femur, tibia, and humerus. Osteochondroma is rare in the diaphysis and in the epiphysis. There was only one case in which a patient had a limited range of motion in the shoulder joint due to an intraarticular osteochondroma of the proximal humerus. We present a rare case of intraarticular osteochondroma involving the proximal humerus with pathologic findings and imaging features on computed tomography and magnetic resonance imaging.

A case of atypical fibroxanthoma of subungual type: ultrasound and magnetic resonance imaging findings

Subungual atypical fibroxanthoma is a rare mesenchymal skin tumor of intermediate malignancy. It classically presents as a relatively nondescript, erythematous nodule; it may ulcerate and bleed, but pain and pruritus are uncommon. In the differential diagnoses of subungual tumors, glomus tumor, soft tissue chondroma, keratoacanthoma, hemangioma, lobular capillary hemangioma, epidermal and mucoid cysts, squamous cell carcinoma, and malignant melanoma have been suggested. But atypical fibroxanthoma has not been included in the differential diagnoses. We report a case that occurred in a 56-year-old man with subungual atypical fibroxanthoma mimicking malignant soft tissue tumor in the right fifth toe.

Prevalence and risk factors of anterior atlantoaxial subluxation in ankylosing spondylitis

OBJECTIVE

In ankylosing spondylitis (AS), the cervical spine, like other sections of the spine and sacroiliac joints, is vulnerable during the disease process. Atlantoaxial subluxation (AAS) has been studied in connection with AS, but its risk factors and progression have not been clarified. Therefore, this study assessed the prevalence and risk factors of AAS in patients with AS.

METHODS

A total of 819 patients with AS who fulfilled the modified New York criteria and were examined with a full-flexion lateral view of the cervical spine by radiograph were enrolled from an outpatient clinic. The medical records of the patients were retrospectively reviewed and the anterior atlantodental interval (AADI) in the lateral flexion view of the cervical spine radiograph was investigated by 2 experienced musculoskeletal radiologists. We defined the AAS as an AADI of > 3 mm, and progression of AADI as a progression rate > 0.5 mm/year.

RESULTS

AAS was found in 14.1% (116/819) of patients. Progression of AADI occurred in 32.1% (26/81) patients with AAS and 5.0% (16/320) patients without AAS (p < 0.001). The development of AAS was significantly associated with elevated C-reactive protein [CRP; OR 2.19 (1.36-3.53)], peripheral arthritis [OR 2.05 (1.36-3.07)], use of anti-tumor necrosis factor antagonists because of failure of nonsteroidal antiinflammatory drugs/disease-modifying antirheumatic drugs [NSAID/DMARD; OR 2.28 (1.52-3.42)], and uveitis [OR 1.71 (1.13-2.59)]. These factors were adjusted for age, sex, and disease duration by logistic regression analysis. No clear association was found for HLA-B27, seropositivity, or smoking status with AAS.

CONCLUSION

AAS is a frequent complication, and the progression of AADI was more rapid in cases with AAS. The presence of peripheral arthritis, or high disease activity with elevated CRP level or refractory to conventional NSAID/DMARD, independently increased the risk of AAS, suggesting that clinicians should focus on the detection and monitoring of AAS, especially in cases with associated risk factors.

Early-onset childhood sarcoidosis with incidental multiple enchondromatosis

The triad of rash, arthritis, and uveitis seems to be characteristic for early-onset childhood sarcoidosis. We describe an interesting case of early-onset childhood sarcoidosis coexisting enchondromatosis, which clinically masquerade as Langerhans cell histiocytosis. A 33 months old girl presented with skin rash, subcutaneous nodules with polyarthritis, and revealed the involvement of lymph nodes as well as spleen during work-up. She also presented with multiple osteolytic lesions which pathologically proven enchondromatosis. Oral prednisone was prescribed at 2 mg/kg/day for 2 months until when subcutaneous nodules and joint swellings almost disappeared, and then slowly tapered over a period of 5 months. We report an unusual case of early-onset childhood sarcoidosis presented with osteolytic bone lesions which were irrelevant to sarcoidosis.

Acute retropharyngeal calcific tendinitis in an unusual location: a case report in a patient with rheumatoid arthritis and atlantoaxial subluxation

Retropharyngeal calcific tendinitis is defined as inflammation of the longus colli muscle and is caused by the deposition of calcium hydroxyapatite crystals, which usually involves the superior oblique fibers of the longus colli muscle from C1-3. Diagnosis is usually made by detecting amorphous calcification and prevertebral soft tissue swelling on radiograph, CT or MRI. In this report, we introduce a case of this disease which was misdiagnosed as a retropharyngeal tuberculous abscess, or a muscle strain of the ongus colli muscle. No calcifications were visible along the vertical fibers of the longus colli muscle. The lesion was located anterior to the C4-5 disc, in a rheumatoid arthritis patient with atlantoaxial subluxation. Calcific tendinitis of the longus colli muscle at this location in a rheumatoid arthritis patient has not been reported in the English literature.

Muscular amyloidoma presenting as inguinal masses in multiple myeloma

We report a case with protruding inguinal masses for 6 months, in whom muscular amyloidoma was not suspected before muscle biopsy. On pelvic magnetic resonance imaging (MRI), round masses showing peripheral rim enhancement with gadolinium were observed in iliopsoas and iliacus muscles of both inguinal areas. The same lesions were also observed in gluteus muscles. The biopsy showed Congo red positive materials in a dense fibrous background. Serum and urine electrophoresis showed Bence Jones protein, lambda type. In bone marrow section, myeloma cells were found. Peripheral blood stem cell transplantation (PBSCT) following four cycles of VAD (vincristine, adriamycin, dexamethasone) chemotherapy was performed and the result was satisfactory. Amyloidoma lesions decreased in size and number on the following MRI.

Angiotensin-converting enzyme gene polymorphism and vascular manifestations in Korean patients with SLE

Systemic lupus erythematosus (SLE) is an inflammatory multisystem disease of unknown etiology with immunologic aberrations. Many studies have shown that genetic and environmental factors are implicated in the development of SLE. Angiotensin-converting enzyme (ACE) affects various immune phenomena through the renin-angiotensin and kallikrein-kininogen systems by creating angiotensin II and inactivating bradykinin. We investigated the correlation between insertion/ deletion polymorphism of the ACE gene and the clinical manifestations of SLE, especially vascular involvement and lupus nephritis. Two-hundred and eleven Korean patients fulfilling the ACR criteria and 114 healthy subjects were enrolled. The ACE genotype was determined by polymerase chain reaction using genomic DNA from peripheral blood. The nephritis patients were classified by the WHO classification. In addition, the activity and chronicity index were used to assess the severity of renal involvement. We evaluated vascular involvement by the presence or absence of hypertension, Raynaud's phenomenon, livedo reticularis, antineutrophil cytoplasmic antibody and the SLICC/ACR Damage Index. The gene frequency of ACE gene polymorphism was as follows: II 39 vs 34%, ID 41 vs 50%, DD 20 vs 16% in SLE patients and controls, respectively. There was no difference in genotype frequency between both groups. There were no significant differences between the distribution of ACE gene genotypes and lupus nephritis and its related parameters, including WHO classification, activity index, chronicity index, renal dysfunction and amount of 24 h urinary protein. The ACE genotypes and alleles did not affect the presence of vascular manifestations evaluated, but the frequency of DD genotype was significantly low in SLE patients with Raynaud's phenomenon compared to those without Raynaud's phenomenon (P = 0.002 for ACE ID vs DD and II, OR 2.7, 95% CI 1.43-5.09; P=0.023 for ACE DD vs ID and II, OR 0.33, 95% CI 0.12-0.89). Also skewing from DD to II genotype was noted in patients with anti-Sm antibody compared to those without anti-Sm antibody (P = 0.025 for ACE DD vs ID and II, OR 0.21, 95% CI 0.05-0.93). The onset age of serositis was older in patients with the ID genotype than the others (ID= 34.5+/-10.8, II + DD = 25.6+/-10.2, P= 0.002). Also the onset age of malar rash was older in patients with II genotype than the others (II=26.7+/-8.4, ID+DD=21.3+/-9.0; P=0.021). The patients with I allele showed a significantly higher frequency of serositis (P = 0.022). Taken together, the I/D polymorphisms of ACE gene did not affect susceptibility of SLE, lupus nephritis and the vascular manifestations, including Raynaud's phenomenon, in Korean SLE patients, although the DD genotype was negatively associated with Raynaud's phenomenon among SLE patients. However, it would be valuable to evaluate the role of other genes potentially related to vascular events, such as endothelin, nitric oxide or angiotensin II receptor as well as ACE gene.

Tuberculous pleural effusion: new pulmonary lesions during treatment

PURPOSE

To evaluate patients who have a paradoxical response (development of new opacities) to treatment for tuberculous pleural effusion not related to acquired immunodeficiency syndrome.

MATERIALS AND METHODS

In 16 patients, follow-up chest radiographs (n = 16) and initial (n = 2) and follow-up (n = 9) computed tomographic (CT) scans of the chest were retrospectively reviewed by two radiologists. Patient records (n = 16) and results of percutaneous needle aspiration and/or biopsy (n = 6) were reviewed by one radiologist.

RESULTS

Eighteen episodes of new lesion development were identified on radiographs in 16 patients. Each episode showed single (nine of 18 episodes, 50%) or multiple (nine of 18 episodes, 50%) nodules, most of which were in the peripheral lung (16 of 18 episodes, 89%) ipsilateral to the side of previous effusion (17 of 18 episodes, 94%). On CT scans, all lesions were peripheral pulmonary nodules, not round atelectasis. Needle aspiration and/or biopsy of the lesions showed findings consistent with tuberculosis in all six patients. Lesions usually evolved within 3 months after the start of medication (13 of 18 episodes) and finally disappeared (15 episodes) or left residual opacities (three episodes) 3-18 months later, with continuation of medication.

CONCLUSION

New lung lesions that develop during medication for tuberculous pleural effusion should be considered a transient worsening that ultimately improves with continuation of medication.

Radiologic changes of cervical spine in ankylosing spondylitis

Ankylosing spondylitis (AS) is characterised by its effects on the axial skeleton. The cervical spine is also vulnerable to the disease process. Our aim was to determine the frequency of radiologic changes to the cervical spine and their correlation with clinical variables. We also used the Bath Ankylosing Spondylitis Radiology Index (BASRI) system, which is one of the reliable scoring systems of radiography, to score the global radiologic changes to the cervical and lumbar spine and the hip joints in our AS cohort. There were 181 patients with anteroposterior and lateral full-flexion views on radiography of the cervical spine here included in the study. A radiologist examined the radiologic changes to all anatomical compartments of the cervical spine in detail and graded them according to the BASRI system. We used the clinical and demographic data of our AS cohort to determine their relation to the radiographic changes. Eighty-eight patients (48.6%) showed radiological changes to the cervical spine; to the discovertebral joint 35.9%; the apophyseal joint 26.0%; atlantoaxial articulation 22.1% (atlantoaxial subluxation 13.8%); the costovertebral joint 18.2%; and to the posterior ligamentous attachment 11.6%. Using the BASRI system, 73 patients (40.3%) showed radiologic changes to the cervical spine and were graded as score 1 (1.7%), 2 (22.7%), 3 (6.6%) or 4 (9.4%). Among those graded as normal by the BASRI system, 17 showed some changes the cervical spine, such as atlantoaxial joint subluxation or narrowing, and severe osteoporosis with no other radiographic changes. Current age, disease duration, inflammatory back pain and cervical symptoms were associated with the radiographic changes to the cervical spine. The BASRI-cervical spine score correlated with the BASRI-lumbar spine and hip joint score, sacroiliitis, disease duration, and duration of inflammatory back pain and cervical symptoms. Our data suggest that radiographic changes to the cervical spine are frequent in AS, and can be predicted in the patients with old age, long duration of disease and inflammatory back pain, and cervical symptoms. Also, the BASRI scoring system showed similar results as a detailed assessment of the cervical spine in our study.

Relationship between sonographic and pathologic findings in epidermal inclusion cysts

PURPOSE

We evaluated the sonographic findings in epidermal inclusion cysts and related them to the pathologic findings.

METHODS

We retrospectively reviewed the sonograms and pathology specimens of 24 patients with pathologically proven epidermal inclusion cysts. We evaluated the lesions for shape, size, internal echogenicity, posterior sound enhancement, and presence of color Doppler signals. We classified the masses into 5 sonographic types according to their internal echogenicity. The relationship between the sonographic types and the pathologic findings was examined.

RESULTS

The masses were ovoid or spherical in 17 cases (71%), lobulated in 5 (21%), and tubular in 2 (8%). The longest diameter ranged from 1 to 6 cm (mean, 3.1 cm). Twenty-three cases (96%) were associated with posterior sound enhancement. Color Doppler signals were absent in 20 cases, but some vascularity was noted in 4 ruptured epidermal cysts, in areas of granulation tissue. The most common sonographic type was a hypoechoic lesion with scattered echogenic reflectors (10 cases). Sonographic findings were related to the lamellation of keratin debris and the granulation tissue secondary to rupture. Most cases with a lobulated configuration (4 of 5) or color Doppler signals (4 of 4) were ruptured cysts.

CONCLUSIONS

Epidermal inclusion cysts most often appeared sonographically as a hypoechoic mass containing variable echogenic foci without color Doppler signals. Ruptured epidermal cysts, however, may have lobulated contours and show color Doppler signals, mimicking a solid mass.

A case of parasymphyseal and associated insufficiency fractures of pubic rami in a patient with mixed connective tissue disease

Parasymphyseal insufficiency fractures are uncommon. Furthermore, none have been reported in systemic rheumatic diseases other than rheumatoid arthritis. In this article we report on parasymphyseal insufficiency fractures in a patient with mixed connective tissue disease.

MR imaging of medullary streaks in osteosclerosis: a case report

We present a case of medullary sclerosis of the appendicular skeleton in a patient with chronic renal insufficiency for whom MR imaging findings were characteristic. T1- and T2-weighted MR images showed multiple vertical lines (medullary streaks) of low signal intensity in the metaphyses and diaphyses of the distal femur and proximal tibia.