Challenges in Dental Statistics: Data and Modelling

The aim of this work is to present the reflections and proposals derived from the first Workshop of the SISMEC STATDENT working group on statistical methods and applications in dentistry, held in Ancona (Italy) on 28th September 2011. STATDENT began as a forum of comparison and discussion for statisticians working in the field of dental research in order to suggest new and improve existing biostatistical and clinical epidemiological methods. During the meeting, we dealt with very important topics of statistical methodology for the analysis of dental data, covering the analysis of hierarchically structured and over-dispersed data, the issue of calibration and reproducibility, as well as some problems related to survey methodology, such as the design and construction of unbiased statistical indicators and of well conducted clinical trials. This paper gathers some of the methodological topics discussed during the meeting, concerning multilevel and zero-inflated models for the analysis of caries data and methods for the training and calibration of raters in dental epidemiology

Six months of high-dose xylitol in high-risk caries subjects—a 2-year randomised, clinical trial

Objectives The hypothesis was that the daily use of a high dose of a xylitol chewing gum for 6 months would reduce the increment of decayed permanent first molar surfaces (ΔD6S) in high-risk schoolchildren after 2 years. Methods In this randomised, clinical trial, 204 schoolchildren with a high caries risk were assigned to two experimental groups, xylitol and non-xylitol. Caries status, salivary mutans streptococci, and lactobacilli were re-evaluated 2 years later in 74 xylitol-treated and 83 non-xylitol-treated schoolchildren. Differences in mean ∆D6S between groups registered at baseline and at follow-up were evaluated using the nonparametric Mann–Whitney U test. Results Outcome was the development of detectable carious lesions initial (D1–D2) and manifest (D3) in the permanent first molars. In the xylitol group, the difference in proportion of children with decayed first permanent molars at baseline and follow-up was 1.43 % for manifest lesion and 2.86 % for initial lesions; while in the non-xylitol group was 10.26 % (p < 0.01) and 16.66 % (p < 0.01), respectively. A statistically significant difference regarding means was also observed in the non-xylitol group: the ∆D6S for manifest lesion was 0.18 (p = 0.03) and 0.67 (p = 0.02) for initial lesion. Conclusion The use of a chewing gum containing a high dose of xylitol for a period of 6 months has been shown to produce a long-term effect on caries development in high caries-risk children. Clinical relevance A school-based preventive programme based on 6 months’ administration of a high dose of xylitol via chewing gum proved to be efficacious in controlling caries increment in high-risk children

Homocysteine and risk of age-related macular degeneration: a systematic review and meta-analysis

There is still no agreement on total plasma homocysteine (tHcy) role in age-related macular degeneration (AMD), the leading cause of new blindness in industrialized countries. We performed a systematic review and meta-analysis of the published data on the correlation between tHcy and AMD. MEDLINE/PubMed and ISI Web of Sciences searches were performed according to MOOSE guidelines. Case-control studies were eligible for inclusion. Participants and controls were AMD patients and subjects without AMD. The main outcome measure was wet AMD. Homocysteine level was the main exposure variable. Data were pooled using a random-effects model. Twelve case-control studies were identified: 10 assessed wet AMD, four dry AMD, one early AMD, one late AMD, and one any AMD. As for wet AMD, there was a total of 453 cases and 514 controls. Mean tHcy was on average 1.1 μmol/l (95% confidence interval [CI] = 0.96-1.25) greater in wet AMD cases, but there was evidence of extreme between-study heterogeneity (p < 0.001, I2 = 91.8%). In a model homogenous for age, including six wet AMD studies (214 cases, 274 controls), mean tHcy was on average 0.58 μmol/l (95% CI = 0.35-0.73) greater in the case group, a not statistically significant result (p = 0.144) associated with moderate heterogeneity (I2 = 39.2%). Our meta-analysis indicates that there is some weak evidence that increased tHcy might be associated with wet AMD; however, this result should be interpreted cautiously, because of a marked between-study heterogeneity and the possible effect of publication bias. Future studies, preferably of cohort design, are necessary before any firm conclusions on the putative role of increased tHcy on AMD can be drawn

La Sorveglianza attiva delle paralisi flaccide acute (AFP)in Sardegna nell'obiettivo della eradicazione della poliomielite

Nella storia della salute pubblica, l’umanità sta per raggiungere un importante obiettivo nel controllo delle malattie infettive, obiettivo fino ad ora conquistato solo per il vaiolo. Nel 1988 l’Assemblea Mondiale della Sanità si è infatti proposta di perseguire, tra i suoi obiettivi, la eradicazione della poliomielite attraverso una strategia di base imperneata su a) garanzia di alti livelli di copertura nella popolazione al di sotto dei 5 anni di età con vaccinazione routinaria utilizzando vaccino antipolio orale tipo Sabin; b) attività supplementari di vaccinazione tipo NID (Giornate Nazionali di Immunizzazione) in quei Paesi in cui la copertura di cui al punto a) è inferiore al 90%; c) interventi di “mopping-up” (vaccinazione di tutti i bambini tra 0 e 5 anni, indipendentemente dal loro stato vaccinale) nelle zone in cui si verificano focolai epidemici; d) sorveglianza di tutte le paralisi flaccide acute (AFP) in modo da identificare con certezza ogni caso di poliomielite. Attualmente, i Paesi liberi dalla polio sono oltre 175* (Fig. 1), mentre rimangono ancora critiche le zone dell’Africa occidentale e centrale (comprese il Corno d’Africa) e il sub continente indiano che continuano a notificare il maggior numero di casi di polio. Per ottenere il riconoscimento della certificazione di “polio-free”, ciascun Paese deve documentare, per un periodo di almeno tre anni consecutivi, l’assenza di casi di malattia paralitica da ceppi selvaggi e l’assenza della circolazione ambientale di poliovirus selvagg

Spectral characterisation of ventricular intracardiac potentials in human post-ischaemic bipolar electrograms

Abnormal ventricular potentials (AVPs) are frequently referred to as high-frequency defections in intracardiac electrograms (EGMs). However, no scientifc study performed a deep spectral characterisation of AVPs and physiological potentials in real bipolar intracardiac recordings across the entire frequency range imposed by their sampling frequency. In this work, the power contributions of post-ischaemic physiological potentials and AVPs, along with some spectral features, were evaluated in the frequency domain and then statistically compared to highlight specific spectral signatures for these signals. To this end, 450 bipolar EGMs from seven patients affected by post-ischaemic ventricular tachycardia were retrospectively annotated by an experienced cardiologist. Given the high variability of the morphologies observed, three different sub-classes of AVPs and two subcategories of post-ischaemic physiological potentials were considered. All signals were acquired by the CARTO\uae 3 system during substrate-guided catheter ablation procedures. Our findings indicated that the main frequency contributions of physiological and pathological post-ischaemic EGMs are found below 320 Hz. Statistical analyses showed that, when biases due to the signal amplitude influence are eliminated, not only physiological potentials show greater contributions below 20 Hz whereas AVPs demonstrate higher spectral contributions above~ 40 Hz, but several finer differences may be observed between the different AVP types

Epidemiology of hydatidosis in the province of Sassari, Italy

Cystic echinococcosis is endemic in certain parts of the world, including Sardinia, Italy. It was performed a study in the province of Sassari in order to evaluate the incidence of the infection in man and the effects of control programs since 1964 to 2002. Data obtained by surgical records, hospital discharge forms, radiological and pathological files were collected using a case report form. During the years 1964- 2002, 2702 new cases were identified (average annual incidence: 17 per 100,000) and 1981 (73.3%) were submitted to surgical treatment. In 57.3% municipalities no cases were observed during the years 1998- 2002. Males are more affected (56.2%), mostly farmers-shepherdess (68.6 per 100,000) and pensioners (59.6 per 100,000). Control measures led to a significant decline in the incidence rate of hydatidosis during the period 1964-2002, dropping by 27.6 per 100,000. The mean age of surgical patients increased during the years of surveillance, such as the surgical liver/lung ratio as a consequence of a cohort effect. The durability of control programs is the corner stone for obtaining a significant decrease of this infection

Caries experience among adolescents in southeast Italy

Abstract Background/purpose According to WHO recommendations, 12-year-olds are considered an important target group for evaluating the level of dental caries among children with permanent teeth, and are often chosen for international comparisons. The aim of the present study was to evaluate the current oral health status of 12-year-old children in southeast Italy, stratified by gender and residential area. Materials and methods The survey was conducted on 431 children enrolled by multistage cluster sampling. A dental caries experience index (decayed, missing, and filled permanent teeth; DMFT) was recorded at schools by a team of examiners trained at the start of the study. Statistical analyses by Chi-square, Fisher's exact, and Wilcoxon tests were performed using SAS version 9.1 software for PCs. We applied the Zero-Inflated Negative Binomial regression model in the STATA package. Results Caries prevalence was recorded in 38.3% of the sample. Estimated means and 95% confidence intervals of the DMFT index by gender were: 1.15 (0.91–1.39) for males, 1.26 (1.02–1.5) for females, and 1.21 (1.03–1.39) for the total sample. The D component of the index was dominant. The mean number of caries found in southeast Italy was significantly higher than the national mean ( t =3.125, P=0.002), but significantly lower than the mean for south Italy ( t =−2.125, P=0.03). Results of the regression model showed that only the mother and father's nationality and educational level contributed to the DMFT. Conclusions The oral health situation of 12-year-old children from southeast Italy seems to be in line with that in other Western European countries

the role of pelvic floor impairment as a contributory factor to urinary incontinence in patients with bladder instability

Unstable bladder symptomatology often includes different types of urinary incontinence. We assessed the possible correlation between urinary incontinence associated with an unstable bladder and pelvic floor activity. In addition, we assessed when oxybutynin administration has favourable effects on urinary incontinence associated with an unstable bladder. Sixty female patients affected by an unstable bladder, consecutively enrolled in the study, were evaluated by means of urodynamics and diagnostic electromyography. Urinary incontinence, when present, was characterized. Possible correlation between types of urinary incontinence and types of pelvic floor dysfunction was investigated. Oxybutynin 5 mg.x3/day was administered per os. Drug activity was evaluated in terms of outcome for the different types of urinary incontinence. A prevailing reduction in maximal muscle contraction and endurance in the patients affected by stress and mixed urinary incontinence was found. 42% of the patients affected by urge incontinence showed a decrease in endurance, and 52% showed overall good functioning of their pelvic floor. Administration of oxybutynin only improved urinary incontinence in those patients affected by urge incontinence who did not have pelvic floor dysfunction (exact Fisher’s test, p<0.001)

Short test evaluation of the anti-wrinkles efficacy of topical adhesive pads

Introduction. In the last decades, in dermo-cosmetic field, a lot of cosmetic products, invasive treatments and medical devices were popping up to improve aged skin. Recently several cheap and innovative products called anti-wrinkle pad adhesive appeared but their efficiency against winkles is not really certain. Theoretically this product is intended to reduce local muscular contraction getting a reduction of the existing winkles and forming new dynamical winkles. Commercial advertisements claims that the utilization of pads can temporarily delete winkles with just an application and last longer with a continuous application. A recent study demonstrated that using this product for a month don’t have any positive effect on forehead wrinkles but still not demonstrate if this pad have the real ability to temporarily reduce wrinkles (Ryan 2009). For this reason this work focus on the efficiency of this pad in crow’s feet temporarily reduction. Materials and Methods. The anti-wrinkles efficiency was valued on 20 volunteers at baseline and 15, 30, 60 minutes after short time (30 minutes) application of the anti?wrinkles pad using Cutometer MPA580® (Courage + Khazaka Electronic GmbH, Köln, Germany) and siliconic replica technique analized with SEM FEI Quanta 200 in low vacuum and profilometric analysis software 3D MEX® (Alicona Imaging, Graz, Austria). Pads are made out of plastic with a vertical strong support fixed at a soft membrane covered by adhesive gel made by emollient and anti-wrinkles materials. Roughness and elasticity differences on values after pads application were valued using analysis of variance (ANOVA). Results. The short time application of the pad caused a relevant reduction of all roughness standards parameters (Ra, Rt, Rz, Rp, Rv) till 15 minutes after the treatment (p <0,001). These changes not happened in the contralateral area (non treatment control test). Within 30 minutes after the treatment, all roughness parameters reverted to normal baseline values. Analysing the elastometric measure average, it was not noticed any relevant standards changes (R0, R5, R6 e R7) after the treatment. Conclusions. Finally results obtained demonstrate that the sporadically application for 30 minutes of anti-wrinkle pad have the capacity to stretch temporarily the skin. Ryan WR, Most SP. A Prospective Evaluation of the Efficacy of Topical Adhesive Pads for the Reduction of Facial Rhytids. Arch Facial Plast Surg. 2009 Jul-Aug;11(4):252-6

Cadmium modifies the cell cycle and apoptotic profiles of human breast cancer cells treated with 5-fluorouracil

Industrialisation, the proximity of factories to cities, and human work activities have led to a disproportionate use of substances containing heavy metals, such as cadmium (Cd), which may have deleterious effects on human health. Carcinogenic effects of Cd and its relationship with breast cancer, among other tumours, have been reported. 5-Fluorouracil (5-FU) is a fluoropyrimidine anticancer drug used to treat solid tumours of the colon, breast, stomach, liver, and pancreas. The purpose of this work was to study the effects of Cd on cell cycle, apoptosis, and gene and protein expression in MCF-7 breast cancer cells treated with 5-FU. Cd altered the cell cycle profile, and its effects were greater when used either alone or in combination with 5-FU compared with 5-FU alone. Cd significantly suppressed apoptosis of MCF-7 cells pre-treated with 5-FU. Regarding gene and protein expression, bcl2 expression was mainly upregulated by all treatments involving Cd. The expression of caspase 8 and caspase 9 was decreased by most of the treatments and at all times evaluated. C-myc expression was increased by all treatments involving Cd, especially 5-FU plus Cd at the half time of treatment. Cd plus 5-FU decreased cyclin D1 and increased cyclin A1 expression. In conclusion, our results indicate that exposure to Cd blocks the anticancer effects of 5-FU in MCF-7 cells. These results could have important clinical implications in patients treated with 5-FU-based therapies and who are exposed to high levels of Cd