Christophe Demattei

Arbitrarily shaped multiple spatial cluster detection for case event data

An original method is proposed for spatial cluster detection of case event data. A selection order and the distance from the nearest neighbour are attributed to each point, once pre-selected points have been taken into account. This distance is weighted by the expected distance under the uniform distribution hypothesis. Potential clusters are located by modelling the multiple structural change of the distances on the selection order and the best model (containing one or several potential clusters) is selected using the double maximum test. Finally a p-value is obtained for each potential cluster. With this method multiple clusters of any shape can be detected.

Autoantibodies to citrullinated fibrinogen compared with anti-MCV and anti-CCP2 antibodies in diagnosing rheumatoid arthritis at an early stage: data from the French ESPOIR cohort

Objectives To compare the performance of anticitrullinated peptides/protein antibodies (ACPA) detected by three immunoassays in the French ESPOIR cohort of patients with early rheumatoid arthritis (RA) and undifferentiated arthritis (UA) and to study the relationship between ACPA and disease activity. Methods A diagnosis of RA (1987 American College of Rheumatology (ACR) criteria) was established at baseline in 497 patients and after a 2-year follow-up in 592 patients. At baseline, antibodies to citrullinated fibrinogen (AhFibA), antimutated citrullinated vimentin (anti-MCV) and anticyclic citrullinated peptide (anti-CCP2) were assayed and the individual and combined diagnostic sensitivities and predictive values of the tests were determined. Relationships between ACPA positivity and the 28-joint disease activity score and Health Assessment Questionnaire scores were analysed. Results At a diagnostic specificity of at least 98%, the three tests exhibited similar diagnostic sensitivities (47–48.5%). When considering as positive patients with at least one positive test, the sensitivity increased to 53.5% with a probable loss of specificity. Among the patients classified as having UA at baseline, 30% were positive for one ACPA, the positive predictive values for RA of the three tests ranging from 73% to 80% but increasing when two tests were associated. Whatever the test used, the addition of ACPA positivity to the 1987 criteria enhanced their sensitivity by 6%, close to that of the 2010 ACR/European League Against Rheumatism (EULAR) criteria. Conclusions In early arthritis, AhFibA, anti-MCV and anti-CCP2 showed similar diagnostic sensitivity with a high diagnostic specificity and a similar high positive predictive value for RA. Adding ACPA to the 1987 ACR criteria significantly increased the number of patients classified as having RA, confirming the validity of the recent inclusion of the serological criterion in the ACR/EULAR criteria.

Bronchial obstructive phenotypes in the first year of life among Paris birth cohort infants.

As the natural history of respiratory and allergic manifestations is unclear, our ongoing Paris birth cohort study prospectively assesses the onset of these symptoms in early childhood. Data were collected by five questionnaires sent at regular intervals during the first year of life. Partitioning around medoids (PAM) was used to classify infants according to their bronchial obstructive symptoms. A polytomous logistic regression was performed to assess the eventual predictable power of various respiratory events and perinatal factors. Results are given for 2698 infants. Atopic dermatitis occurred in 17.9% of infants. The main respiratory symptoms in infancy were wheeze in the chest (22%), dyspnoea responsible for sleep disturbance (23.7%), nocturnal dry cough (14.5%) and shortness of breath (4.2%). The PAM method identified three groups of infants. Apart from the G0 group of infants mostly asymptomatic, two distinct clinical phenotypes (G1 and G2: 8.7% and 23.5% of total infants respectively) emerged. G2 was defined by severe bronchial obstructive disorders as all cases of dyspnoea with sleep disturbance were included in this group, while all infants assigned in G1 suffered from nocturnal dry cough. G2 group infants had significantly higher rates of respiratory events while a parental history of asthma, symptoms suggestive of rhino‐conjunctivitis and birth season clearly differentiated the G1 group. Finally, G1 and G2 group infants should be closely followed up as they are expected to develop allergic and asthmatic phenotypes, possibly in relation to environmental and behavioural risk factors.

Impact of uveitis on the phenotype of patients with recent inflammatory back pain: data from a prospective multicenter French cohort.

To determine the prevalence of uveitis in patients with recent inflammatory back pain (IBP) suggestive of spondylarthritis (SpA), and to investigate the impact of uveitis on the overall features of these patients.

Anterior chest wall pain in recent inflammatory back pain suggestive of spondyloarthritis. data from the DESIR cohort.

Objective. To determine the prevalence of anterior chest wall (ACW) pain in patients with recent inflammatory back pain (IBP) suggestive of spondyloarthritis (SpA), and to investigate the influence of ACW pain on the overall features of these patients. Methods. The DESIR cohort is a prospective, multicenter French cohort of patients with early IBP suggestive of SpA, including 708 patients (mean age 33.8 yrs, 53.8% females, 57.3% HLA-B27-positive). ACW pain was defined by at least 1 episode of chest wall pain attributed to SpA by the rheumatologist, after ruling out other causes of chest pain. Data on the baseline demographic characteristics, functional status and quality of life, imaging features, bone mineral density, and blood tests were compared in patients with and those without ACW pain. Factors associated with ACW pain were identified by univariate and multivariate analysis (logistic regression). Results. The prevalence of ACW pain in the DESIR cohort (n = 316/708 patients) was 44.6% (95% CI 40.9–48.3). ACW pain occurred after the first symptoms of IBP in 62%. Localization was diffuse in 41% of the positive cases. A stepwise multivariate analysis found an association between ACW pain and the enthesitis score, involvement of thoracic spine, diagnosis of ankylosing spondylitis (AS), and radiographic abnormalities of sacroiliac joints. Conclusion. In recent IBP suggestive of SpA, presence of ACW pain is associated with enthesitis, thoracic spine involvement, radiographic sacroiliitis, diagnosis of AS, and with a more severe disease. ACW pain could be interpreted as a diagnostic feature for AS.

Rate and Predisposing Factors for Sacroiliac Joint Radiographic Progression After a Two-Year Follow-up Period in Recent-Onset Spondyloarthritis

To evaluate the rate of radiographic structural progression in the sacroiliac (SI) joints in patients with radiographic or nonradiographic axial spondyloarthritis (SpA), and to determine factors predisposing to such progression, over 2 years.

SPATCLUS: An R package for arbitrarily shaped multiple spatial cluster detection for case event data

This paper describes an R package, named SPATCLUS that implements a method recently proposed for spatial cluster detection of case event data. This method is based on a data transformation. This transformation is achieved by the definition of a trajectory, which allows to attribute to each point a selection order and the distance to its nearest neighbour. The nearest point is searched among the points which have not yet been selected in the trajectory. Due to the trajectory effects, the distance is weighted by the expected distance under the uniform distribution hypothesis. Potential clusters are located by using multiple structural change models and a dynamic programming algorithm. The double maximum test allows to select the best model. The significativity of potential clusters is determined by Monte Carlo simulations. This method makes it possible the detection of multiple clusters of any shape.

Precision of estimates of local stability of repetitive trunk movements

PurposeLocal dynamic stability of trunk movements quantified by means of the maximum Lyapunov exponent (λmax) can provide information on trunk motor control and might offer a measure of trunk control in low-back pain patients. It is unknown how many repetitions are necessary to obtain sufficiently precise estimates of λmax and whether fatigue effects on λmax can be avoided while increasing the number of repetitions.MethodTen healthy subjects performed 100 repetitions of trunk movements in flexion, of trunk rotation and of a task combining these movement directions. λmax was calculated from thorax, pelvis and trunk (thorax relative to pelvis) kinematics. Data series were analyzed using a bootstrap procedure; ICC and coefficient of variation were used to quantify precision as a function of the number of cycles analyzed. ANOVA was used to compare movement tasks and to test for effects of time.ResultsTrunk local stability reached acceptable precision level after 30 repetitions. λmax was higher (indicating lower stability) in flexion, compared to rotation and combined tasks. There was no time effect (fatigue). λmax of trunk movement was lower and less variable than that of thorax and pelvis movements.ConclusionsThe data provided allow for an informed choice of the number of repetitions in assessing local dynamic stability of trunk movements, weighting the gain in precision against the increase in measurement effort. Within the 100 repetitions tested, fatigue did not affect results. We suggest that increased stability during asymmetric movement may be explained by higher co-activation of trunk muscles.

Impact of the Adaptive Statistical Iterative Reconstruction Technique on Radiation Dose and Image Quality in Bone SPECT/CT

The purpose of this study was to compare a routine bone SPECT/CT protocol using CT reconstructed with filtered backprojection (FBP) with an optimized protocol using low-dose CT images reconstructed with adaptive statistical iterative reconstruction (ASiR). Methods: In this prospective study, enrolled patients underwent bone SPECT/CT, with 1 SPECT acquisition followed by 2 randomized CT acquisitions: FBP CT (FBP; noise index, 25) and ASiR CT (70% ASiR; noise index, 40). The image quality of both attenuation-corrected SPECT and CT images was visually (5-point Likert scale, 2 interpreters) and quantitatively (contrast ratio [CR] and signal-to-noise ratio [SNR]) estimated. The CT dose index volume, dose–length product, and effective dose were compared. Results: Seventy-five patients were enrolled in the study. Quantitative attenuation-corrected SPECT evaluation showed no inferiority for contrast ratio and SNR issued from FBP CT or ASiR CT (respectively, 13.41 ± 7.83 vs. 13.45 ± 7.99 and 2.33 ± 0.83 vs. 2.32 ± 0.84). Qualitative image analysis showed no difference between attenuation-corrected SPECT images issued from FBP CT or ASiR CT for both interpreters (respectively, 3.5 ± 0.6 vs. 3.5 ± 0.6 and 3.6 ± 0.5 vs. 3.6 ± 0.5). Quantitative CT evaluation showed no inferiority for SNR between FBP and ASiR CT images (respectively, 0.93 ± 0.16 and 1.07 ± 0.17). Qualitative image analysis showed no quality difference between FBP and ASiR CT images for both interpreters (respectively, 3.8 ± 0.5 vs. 3.6 ± 0.5 and 4.0 ± 0.1 vs. 4.0 ± 0.2). Mean CT dose index volume, dose–length product, and effective dose for ASiR CT (3.0 ± 2.0 mGy, 148 ± 85 mGy⋅cm, and 2.2 ± 1.3 mSv) were significantly lower than for FBP CT (8.5 ± 3.7 mGy, 365 ± 160 mGy⋅cm, and 5.5 ± 2.4 mSv). Conclusion: The use of 70% ASiR blending in bone SPECT/CT can reduce the CT radiation dose by 60%, with no sacrifice in attenuation-corrected SPECT and CT image quality, compared with the conventional protocol using FBP CT reconstruction technique.

Cranberry capsules to prevent nosocomial urinary tract bacteriuria after pelvic surgery: a randomised controlled trial

To evaluate whether cranberries are able to prevent postoperative urinary bacteriuria in patients undergoing pelvic surgery and receiving transurethral catheterisation.