Percutaneous coronary revascularization in patients with formerly "refractory angina pectoris in end-stage coronary artery disease" - not "end-stage" after all

BACKGROUND: Patients with refractory angina pectoris in end-stage coronary artery disease represent a severe condition with a higher reduction of life-expectancy and quality of life as compared to patients with stable coronary artery disease. It was the purpose of this study to invasively re-evaluate highly symptomatic patients with formerly diagnosed refractory angina pectoris in end-stage coronary artery disease for feasible options of myocardial revascularization. METHODS: Thirty-four patients formerly characterized as having end stage coronary artery disease with refractory angina pectoris were retrospectively followed for coronary interventions. RESULTS: Of those 34 patients 21 (61.8%) were eventually revascularized with percutaneous interventional revascularization (PCI). Due to complex coronary morphology (angulation, chronic total occlusion) PCI demanded an above-average amount of time (66 +/- 42 minutes, range 25-206 minutes) and materials (contrast media 247 +/- 209 ml, range 50-750 ml; PCI guiding wires 2.0 +/- 1.4, range 1-6 wires). Of PCI patients 7 (33.3%) showed a new lesion as a sign of progression of atherosclerosis. Clinical success rate with a reduction to angina class II or lower was 71.4% at 30 days. Surgery was performed in a total of8 (23.5%) patients with a clinical success rate of 62.5%. Based on an intention-to-treat 2 patients of originally 8 (25%) demonstrated clinical success. Mortality during follow-up (1-18 months) was 4.8% in patients who underwent PCI, 25% in patients treated surgically and 25% in those only treated medically. CONCLUSION: The majority of patients with end-stage coronary artery disease can be treated effectively with conventional invasive treatment modalities. Therefore even though it is challenging and demanding PCI should be considered as a first choice before experimental interventions are considered.

Prognostic clinical and radiological parameters for immediate facial nerve function following vestibular schwannoma surgery

OBJECTIVE: The paper aims to define the parameters available before surgery which could predict immediate facial nerve function after excision of a vestibular schwannoma (VS). METHODS: Ninety-nine patients with VS operated consecutively by a single surgeon using an identical surgical technique have been evaluated retrospectively. Data were collected regarding patients' sex, age at onset of symptoms and at surgery, initial symptoms, neurological status at presentation, early post-operative neurological status and complications. The main radiological parameters included in the study were tumour extension pattern, diameters, shape, and volume, as well as extent of bony changes of the internal auditory canal. RESULTS: As the tumour stage and volume increase, facial nerve function is worse after surgery (p < 0.001 and p < 0.05, respectively). Concomitantly, larger extra-meatal tumour diameters in three dimensions (sagittal, coronal and axial) led to worse function (p < 0.01). Anterior and/or caudal tumour extension (p = 0.001 and p = 0.004, respectively) had more significant correlation than posterior and/or cranial extension (p = 0.022 and p = 0.353, respectively). Polycyclic VS had the worst prognosis, followed by the tumours with oval shape. The extent of intra-meatal tumour growth does not correlate with immediate facial nerve outcome. The different angles, lengths and diameters of the internal auditory channel showed no significant correlation with facial nerve outcome. Patients with headache as an initial symptom and those with gait instability and/or pre-operative poor facial nerve function had significantly worse immediate facial nerve outcome. CONCLUSION: Our data suggests that the analysis of the radiological and neurological patient data prior to surgery could give reliable clues regarding the immediate post-operative facial nerve function.

Neoadjuvant chemotherapy and radiotherapy followed by surgery in selected patients with stage IIIB non-small-cell lung cancer: a multicentre phase II trial

BACKGROUND: Stage IIIB non-small-cell lung cancer (NSCLC) is usually thought to be unresectable, and is managed with chemotherapy with or without radiotherapy. However, selected patients might benefit from surgical resection after neoadjuvant chemotherapy and radiotherapy. The aim of this multicentre, phase II trial was to assess the efficacy and toxicity of a neoadjuvant chemotherapy and radiotherapy followed by surgery in patients with technically operable stage IIIB NSCLC. METHODS: Between September, 2001, and May, 2006, patients with pathologically proven and technically resectable stage IIIB NSCLC were sequentially treated with three cycles of neoadjuvant chemotherapy (cisplatin with docetaxel), immediately followed by accelerated concomitant boost radiotherapy (44 Gy in 22 fractions) and definitive surgery. The primary endpoint was event-free survival at 12 months. Efficacy analyses were done by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00030810. FINDINGS: 46 patients were enrolled, with a median age of 60 years (range 28-70). 13 (28%) patients had N3 disease, 36 (78%) had T4 disease. All patients received chemotherapy; 35 (76%) patients received radiotherapy. The main toxicities during chemotherapy were neutropenia (25 patients [54%] at grade 3 or 4) and febrile neutropenia (nine [20%]); the main toxicity after radiotherapy was oesophagitis (ten patients [29%]; nine grade 2, one grade 3). 35 patients (76%) underwent surgery, with pneumonectomy in 17 patients. A complete (R0) resection was achieved in 27 patients. Peri-operative complications occurred in 14 patients, including two deaths (30-day mortality 5.7%). Seven patients required a second surgical intervention. Pathological mediastinal downstaging was seen in 11 of the 28 patients who had lymph-node involvement at enrolment, a complete pathological response was seen in six patients. Event-free survival at 12 months was 54% (95% CI 39-67). After a median follow-up of 58 months, the median overall survival was 29 months (95% CI 16.1-NA), with survival at 1, 3, and 5 years of 67% (95% CI 52-79), 47% (32-61), and 40% (24-55). INTERPRETATION: A treatment strategy of neoadjuvant chemotherapy and radiotherapy followed by surgery is feasible in selected patients. Toxicity is considerable, but manageable. Survival compares favourably with historical results of combined treatment for less advanced stage IIIA disease. FUNDING: Swiss Group for Clinical Cancer Research (SAKK) and an unrestricted educational grant by Sanofi-Aventis (Switzerland).

TGF-ß1 enhances the BMP-2-induced chondrogenesis of bovine synovial explants and arrests downstream differentiation at an early stage of hypertrophy

BACKGROUND Synovial explants furnish an in-situ population of mesenchymal stem cells for the repair of articular cartilage. Although bone morphogenetic protein 2 (BMP-2) induces the chondrogenesis of bovine synovial explants, the cartilage formed is neither homogeneously distributed nor of an exclusively hyaline type. Furthermore, the downstream differentiation of chondrocytes proceeds to the stage of terminal hypertrophy, which is inextricably coupled with undesired matrix mineralization. With a view to optimizing BMP-2-induced chondrogenesis, the modulating influences of fibroblast growth factor 2 (FGF-2) and transforming growth factor beta 1 (TGF-ß1) were investigated. METHODOLOGY/PRINCIPAL FINDINGS Explants of bovine calf metacarpal synovium were exposed to BMP-2 (200 ng/ml) for 4 (or 6) weeks. FGF-2 (10 ng/ml) or TGF-ß1 (10 ng/ml) was introduced at the onset of incubation and was present either during the first week of culturing alone or throughout its entire course. FGF-2 enhanced the BMP-2-induced increase in metachromatic staining for glycosaminoglycans (GAGs) only when it was present during the first week of culturing alone. TGF-ß1 enhanced not only the BMP-2-induced increase in metachromasia (to a greater degree than FGF-2), but also the biochemically-assayed accumulation of GAGs, when it was present throughout the entire culturing period; in addition, it arrested the downstream differentiation of cells at an early stage of hypertrophy. These findings were corroborated by an analysis of the gene- and protein-expression levels of key cartilaginous markers and by an estimation of individual cell volume. CONCLUSIONS/SIGNIFICANCE TGF-ß1 enhances the BMP-2-induced chondrogenesis of bovine synovial explants, improves the hyaline-like properties of the neocartilage, and arrests the downstream differentiation of cells at an early stage of hypertrophy. With the prospect of engineering a mature, truly articular type of cartilage in the context of clinical repair, our findings will be of importance in fine-tuning the stimulation protocol for the optimal chondrogenic differentiation of synovial explants.

Characterization and Clinical Relevance of ALDHbright Populations in Prostate Cancer

PURPOSE High aldehyde dehydrogenase (ALDH) has been suggested to selectively mark cells with high tumorigenic potential in established prostate cancer cell lines. However, the existence of cells with high ALDH activity (ALDH(bright)) in primary prostate cancer specimens has not been shown so far. We investigated the presence, phenotype, and clinical significance of ALDH(bright) populations in clinical prostate cancer specimens. EXPERIMENTAL DESIGN We used ALDEFLUOR technology and fluorescence-activated cell-sorting (FACS) staining to identify and characterize ALDH(bright) populations in cells freshly isolated from clinical prostate cancer specimens. Expression of genes encoding ALDH-specific isoforms was evaluated by quantitative real-time PCR in normal prostate, benign prostatic hyperplasia (BPH), and prostate cancer tissues. ALDH1A1-specific expression and prognostic significance were assessed by staining two tissue microarrays that included more than 500 samples of BPH, prostatic intraepithelial neoplasia (PIN), and multistage prostate cancer. RESULTS ALDH(bright) cells were detectable in freshly excised prostate cancer specimens (n = 39) and were mainly included within the EpCAM((+)) and Trop2((+)) cell populations. Although several ALDH isoforms were expressed to high extents in prostate cancer, only ALDH1A1 gene expression significantly correlated with ALDH activity (P < 0.01) and was increased in cancers with high Gleason scores (P = 0.03). Most importantly, ALDH1A1 protein was expressed significantly more frequently and at higher levels in advanced-stage than in low-stage prostate cancer and BPH. Notably, ALDH1A1 positivity was associated with poor survival (P = 0.02) in hormone-naïve patients. CONCLUSIONS Our data indicate that ALDH contributes to the identification of subsets of prostate cancer cells of potentially high clinical relevance.

Carboplatin and paclitaxel plus ASA404 as first-line chemotherapy for extensive-stage small-cell lung cancer: a multicenter single arm phase II trial (SAKK 15/08)

INTRODUCTION Small-cell lung cancer (SCLC) is a highly vascularized tumor. ASA404 is a tumor vascular disrupting agent. This is the first trial to report the effects of combining chemotherapy with ASA404 in SCLC. METHODS Patients with untreated metastatic SCLC were treated with carboplatin (area under curve, 6) plus paclitaxel (175 mg/m(2)) plus ASA404 (1800 mg/m(2)) on day 1 every 21 days for up to 6 cycles. The primary endpoint was the progression-free survival (PFS) rate at 24 weeks. RESULTS Median age was 61 years; 53% were women, 41% had weight loss; and 96% had a performance status of 0-1. Twelve patients completed all 6 cycles, and most adverse events were related to chemotherapy. Median PFS and time to progression were 7.0 months (95% CI, 5.7-9.4 months) and 7.5 months (95% CI, 5.7-9.4 months), respectively. The progression-free survival (PFS) rate at 24 weeks was 41% (95% CI, 18%-65%). The overall response rate was 94%. The median overall survival time was 14.2 months (95% CI, 8.2-16.0 months) and 1-year survival was 57%. The median follow-up time was 17.7 months. Due to negative results with ASA404 in non-small-cell lung cancer trials, the trial was stopped prematurely after 17 of 56 planned patients were being accrued. CONCLUSIONS This is the first report of a clinical trial with a vascular disrupting agent in SCLC. No unexpected toxicity was observed. PFS was not prolonged with carboplatin and paclitaxel plus ASA404.

Macular hole surgery in patients with end-stage choroideremia

OBJECTIVE To assess macular hole surgery in patients with end-stage choroideremia with regard to anatomic closure and visual outcome. DESIGN Retrospective, interventional case series. PARTICIPANTS Thirty adult male patients with a diagnosis of advanced choroideremia were reviewed and underwent spectral domain optical coherence tomography (OCT) as part of the screening process for a gene therapy clinical trial. From within that cohort, 3 were identified as having a full-thickness macular hole (FTMH). METHODS A 23-gauge pars plana vitrectomy was performed with peeling of the inner limiting membrane and gas tamponade. Preoperative best-corrected visual acuity ranged from perception of light to 6/24. MAIN OUTCOME MEASURES Prevalence of FTMH in advanced choroideremia, morphologic phenotype characteristics of FTMH in OCT, pre- and postoperative best-corrected visual acuity, and closure rate after surgery. RESULTS The prevalence of FTMH in advanced choroideremia in our cohort was 10%. One hole was associated with significant macular schisis, presumed to be attributable to degeneration of outer retinal layers. Anatomic closure was achieved in all 3 patients and confirmed with spectral domain OCT. Gas tamponade lasted approximately twice as long as might be expected compared with standard FTMH surgery. Objective visual acuity did not improve; however, perceived vision improved in all patients. CONCLUSIONS Although FTMH in choroideremia is a rare finding, it could potentially mask central progression of the disease. Regular screening may help to diagnose holes at an earlier stage when the visual prognosis after surgery may be better. Standard macular hole surgery seems to be effective in gaining anatomic closure, which would be significant for patients who subsequently require macula detachment for subretinal gene therapy. FINANCIAL DISCLOSURE(S) The authors have no proprietary or commercial interest in any of the materials discussed in this article.

A reliable risk score for stage IV esophagogastric cancer

BACKGROUND The role of surgery for patients with metastatic esophagogastric adenocarcinoma (EGC) is not defined. The purpose of this study was to define selection criteria for patients who may benefit from resection following systemic chemotherapy. METHODS From 1987 to 2007, 160 patients presenting with synchronous metastatic EGC (cT3/4 cNany cM0/1 finally pM1) were treated with chemotherapy followed by resection of the primary tumor and metastases. Clinical and histopathological data, site and number of metastases were analyzed. A prognostic score was established and validated in a second cohort from another academic center (n = 32). RESULTS The median survival (MS) in cohort 1 was 13.6 months. Significant prognostic factors were grading (p = 0.046), ypT- (p = 0.001), ypN- (p = 0.011) and R-category (p = 0.015), lymphangiosis (p = 0.021), clinical (p = 0.004) and histopathological response (p = 0.006), but not localization or number of metastases. The addition of grading (G1/2:0 points; G3/4:1 points), clinical response (responder: 0; nonresponder: 1) and R-category (complete:0; R1:1; R2:2) defines two groups of patients with significantly different survival (p = 0.001) [low risk group (Score 0/1), n = 22: MS 35.3 months, 3-year-survival 47.6%); high risk group (Score 2/3/4) n = 126: MS 12.0 months, 3-year-survival 14.2%]. The score showed a strong trend in the validation cohort (p = 0.063) [low risk group (MS not reached, 3-year-survival 57.1%); high risk group (MS 19.9 months, 3-year-survival 6.7%)]. CONCLUSION We observed long-term survival after resection of metastatic EGC. A simple clinical score may help to identify a subgroup of patients with a high chance of benefit from resection. However, the accurate estimation of achieving a complete resection, which is an integral element of the score, remains challenging.

Clinical impact of programmed cell death ligand 1 expression in colorectal cancer

BACKGROUND Programmed cell death 1 (PD-1) receptor triggering by PD ligand 1 (PD-L1) inhibits T cell activation. PD-L1 expression was detected in different malignancies and associated with poor prognosis. Therapeutic antibodies inhibiting PD-1/PD-L1 interaction have been developed. MATERIALS AND METHODS A tissue microarray (n=1491) including healthy colon mucosa and clinically annotated colorectal cancer (CRC) specimens was stained with two PD-L1 specific antibody preparations. Surgically excised CRC specimens were enzymatically digested and analysed for cluster of differentiation 8 (CD8) and PD-1 expression. RESULTS Strong PD-L1 expression was observed in 37% of mismatch repair (MMR)-proficient and in 29% of MMR-deficient CRC. In MMR-proficient CRC strong PD-L1 expression correlated with infiltration by CD8(+) lymphocytes (P=0.0001) which did not express PD-1. In univariate analysis, strong PD-L1 expression in MMR-proficient CRC was significantly associated with early T stage, absence of lymph node metastases, lower tumour grade, absence of vascular invasion and significantly improved survival in training (P=0.0001) and validation (P=0.03) sets. A similar trend (P=0.052) was also detectable in multivariate analysis including age, sex, T stage, N stage, tumour grade, vascular invasion, invasive margin and MMR status. Interestingly, programmed death receptor ligand 1 (PDL-1) and interferon (IFN)-γ gene expression, as detected by quantitative reverse transcriptase polymerase chain reaction (RT-PCR) in fresh frozen CRC specimens (n=42) were found to be significantly associated (r=0.33, P=0.03). CONCLUSION PD-L1 expression is paradoxically associated with improved survival in MMR-proficient CRC.

Improving the clinical prediction of psychosis by combining ultra-high risk criteria and cognitive basic symptoms

OBJECTIVE Cognitive impairments are regarded as a core component of schizophrenia. However, the cognitive dimension of psychosis is hardly considered by ultra-high risk (UHR) criteria. Therefore, we studied whether the combination of symptomatic UHR criteria and the basic symptom criterion "cognitive disturbances" (COGDIS) is superior in predicting first-episode psychosis. METHOD In a naturalistic 48-month follow-up study, the conversion rate to first-episode psychosis was studied in 246 outpatients of an early detection of psychosis service (FETZ); thereby, the association between conversion, and the combined and singular use of UHR criteria and COGDIS was compared. RESULTS Patients that met UHR criteria and COGDIS (n=127) at baseline had a significantly higher risk of conversion (hr=0.66 at month 48) and a shorter time to conversion than patients that met only UHR criteria (n=37; hr=0.28) or only COGDIS (n=30; hr=0.23). Furthermore, the risk of conversion was higher for the combined criteria than for UHR criteria (n=164; hr=0.56 at month 48) and COGDIS (n=158; hr=0.56 at month 48) when considered irrespective of each other. CONCLUSIONS Our findings support the merits of considering both COGDIS and UHR criteria in the early detection of persons who are at high risk of developing a first psychotic episode within 48months. Applying both sets of criteria improves sensitivity and individual risk estimation, and may thereby support the development of stage-targeted interventions. Moreover, since the combined approach enables the identification of considerably more homogeneous at-risk samples, it should support both preventive and basic research.

Time to renal disease and end-stage renal disease in PROFILE: a multiethnic lupus cohort.

BACKGROUND: Renal involvement is a serious manifestation of systemic lupus erythematosus (SLE); it may portend a poor prognosis as it may lead to end-stage renal disease (ESRD). The purpose of this study was to determine the factors predicting the development of renal involvement and its progression to ESRD in a multi-ethnic SLE cohort (PROFILE). METHODS AND FINDINGS: PROFILE includes SLE patients from five different United States institutions. We examined at baseline the socioeconomic-demographic, clinical, and genetic variables associated with the development of renal involvement and its progression to ESRD by univariable and multivariable Cox proportional hazards regression analyses. Analyses of onset of renal involvement included only patients with renal involvement after SLE diagnosis (n = 229). Analyses of ESRD included all patients, regardless of whether renal involvement occurred before, at, or after SLE diagnosis (34 of 438 patients). In addition, we performed a multivariable logistic regression analysis of the variables associated with the development of renal involvement at any time during the course of SLE.In the time-dependent multivariable analysis, patients developing renal involvement were more likely to have more American College of Rheumatology criteria for SLE, and to be younger, hypertensive, and of African-American or Hispanic (from Texas) ethnicity. Alternative regression models were consistent with these results. In addition to greater accrued disease damage (renal damage excluded), younger age, and Hispanic ethnicity (from Texas), homozygosity for the valine allele of FcgammaRIIIa (FCGR3A*GG) was a significant predictor of ESRD. Results from the multivariable logistic regression model that included all cases of renal involvement were consistent with those from the Cox model. CONCLUSIONS: Fcgamma receptor genotype is a risk factor for progression of renal disease to ESRD. Since the frequency distribution of FCGR3A alleles does not vary significantly among the ethnic groups studied, the additional factors underlying the ethnic disparities in renal disease progression remain to be elucidated.

Discrete Improvement in Racial Disparity in Survival among Patients with Stage IV Colorectal Cancer: a 21-Year Population-Based Analysis

Purpose Recently, multiple clinical trials have demonstrated improved outcomes in patients with metastatic colorectal cancer. This study investigated if the improved survival is race dependent. Patients and Methods Overall and cancer-specific survival of 77,490 White and Black patients with metastatic colorectal cancer from the 1988–2008 Surveillance Epidemiology and End Results registry were compared using unadjusted and multivariable adjusted Cox proportional hazard regression as well as competing risk analyses. Results Median age was 69 years, 47.4 % were female and 86.0 % White. Median survival was 11 months overall, with an overall increase from 8 to 14 months between 1988 and 2008. Overall survival increased from 8 to 14 months for White, and from 6 to 13 months for Black patients. After multivariable adjustment, the following parameters were associated with better survival: White, female, younger, better educated and married patients, patients with higher income and living in urban areas, patients with rectosigmoid junction and rectal cancer, undergoing cancer-directed surgery, having well/moderately differentiated, and N0 tumors (p<0.05 for all covariates). Discrepancies in overall survival based on race did not change significantly over time; however, there was a significant decrease of cancer-specific survival discrepancies over time between White and Black patients with a hazard ratio of 0.995 (95 % confidence interval 0.991–1.000) per year (p=0.03). Conclusion A clinically relevant overall survival increase was found from 1988 to 2008 in this population-based analysis for both White and Black patients with metastatic colorectal cancer. Although both White and Black patients benefitted from this improvement, a slight discrepancy between the two groups remained.

Clinical relevance of brain volume measures in multiple sclerosis.

Multiple sclerosis (MS) is a chronic disease with an inflammatory and neurodegenerative pathology. Axonal loss and neurodegeneration occurs early in the disease course and may lead to irreversible neurological impairment. Changes in brain volume, observed from the earliest stage of MS and proceeding throughout the disease course, may be an accurate measure of neurodegeneration and tissue damage. There are a number of magnetic resonance imaging-based methods for determining global or regional brain volume, including cross-sectional (e.g. brain parenchymal fraction) and longitudinal techniques (e.g. SIENA [Structural Image Evaluation using Normalization of Atrophy]). Although these methods are sensitive and reproducible, caution must be exercised when interpreting brain volume data, as numerous factors (e.g. pseudoatrophy) may have a confounding effect on measurements, especially in a disease with complex pathological substrates such as MS. Brain volume loss has been correlated with disability progression and cognitive impairment in MS, with the loss of grey matter volume more closely correlated with clinical measures than loss of white matter volume. Preventing brain volume loss may therefore have important clinical implications affecting treatment decisions, with several clinical trials now demonstrating an effect of disease-modifying treatments (DMTs) on reducing brain volume loss. In clinical practice, it may therefore be important to consider the potential impact of a therapy on reducing the rate of brain volume loss. This article reviews the measurement of brain volume in clinical trials and practice, the effect of DMTs on brain volume change across trials and the clinical relevance of brain volume loss in MS.

Prognostic factors for advanced-stage human immunodeficiency virus-associated classical Hodgkin lymphoma treated with doxorubicin, bleomycin, vinblastine, and dacarbazine plus combined antiretroviral therapy: A multi-institutional retrospective study.

BACKGROUND The treatment and outcomes of patients with human immunodeficiency virus (HIV)-associated Hodgkin lymphoma (HL) continue to evolve. The International Prognostic Score (IPS) is used to predict the survival of patients with advanced-stage HL, but it has not been validated in patients with HIV infection. METHODS This was a multi-institutional, retrospective study of 229 patients with HIV-associated, advanced-stage, classical HL who received doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) plus combination antiretroviral therapy. Their clinical characteristics were presented descriptively, and multivariate analyses were performed to identify the factors that were predictive of response and prognostic of progression-free survival (PFS) and overall survival (OS). RESULTS The overall and complete response rates to ABVD in patients with HIV-associated HL were 91% and 83%, respectively. After a median follow-up of 5 years, the 5-year PFS and OS rates were 69% and 78%, respectively. In multivariate analyses, there was a trend toward an IPS score >3 as an adverse factor for PFS (hazard ratio [HR], 1.49; P=.15) and OS (HR, 1.84; P=.06). A cluster of differentiation 4 (CD4)-positive (T-helper) cell count <200 cells/μL was associated independently with both PFS (HR, 2.60; P=.002) and OS (HR, 2.04; P=.04). The CD4-positive cell count was associated with an increased incidence of death from other causes (HR, 2.64; P=.04) but not with death from HL-related causes (HR, 1.55; P=.32). CONCLUSIONS The current results indicate excellent response and survival rates in patients with HIV-associated, advanced-stage, classical HL who receive ABVD and combination antiretroviral therapy as well as the prognostic value of the CD4-positive cell count at the time of lymphoma diagnosis for PFS and OS. Cancer 2014. © 2014 American Cancer Society.

Factorial designs: an overview with applications to orthodontic clinical trials.

Factorial designs for clinical trials are often encountered in medical, dental, and orthodontic research. Factorial designs assess two or more interventions simultaneously and the main advantage of this design is its efficiency in terms of sample size as more than one intervention may be assessed on the same participants. However, the factorial design is efficient only under the assumption of no interaction (no effect modification) between the treatments under investigation and, therefore, this should be considered at the design stage. Conversely, the factorial study design may also be used for the purpose of detecting an interaction between two interventions if the study is powered accordingly. However, a factorial design powered to detect an interaction has no advantage in terms of the required sample size compared to a multi-arm parallel trial for assessing more than one intervention. It is the purpose of this article to highlight the methodological issues that should be considered when planning, analysing, and reporting the simplest form of this design, which is the 2 × 2 factorial design. An example from the field of orthodontics using two parameters (bracket type and wire type) on maxillary incisor torque loss will be utilized in order to explain the design requirements, the advantages and disadvantages of this design, and its application in orthodontic research.