Assessing risk stratification in long-term outcomes of rectal neuroendocrine tumors following endoscopic resection: a multicenter retrospective study.

OBJECTIVES: While endoscopic resection of rectal neuroendocrine tumors (NETs) has significantly increased, long-term data on risk factors for recurrence are still lacking. Our aim is to analyze the long-term outcomes of patients with rectal NETs after endoscopic resection through risk stratification. METHODS: In this multicenter retrospective study, we included patients who underwent endoscopic resection of rectal NETs from 2009 to 2018 and were followed for ≥12 months at five university hospitals. We classified the patients into three risk groups according to the clinicopathological status of the rectal neuroendocrine tumors: low, indeterminate, and high. The high-risk group was defined if the tumors have any of the followings: size ≥ 10 mm, lymphovascular invasion, muscularis propria or deeper invasion, positive resection margins, or mitotic count ≥2/10. RESULTS: A total of 346 patients were included, with 144 (41.6%), 121 (35.0%), and 81 (23.4%) classified into the low-, indeterminate-, and high-risk groups, respectively. Among the high-risk group, seven patients (8.6%) received salvage treatment 28 (27-67) days after the initial endoscopic resection, with no reported extracolonic recurrence. Throughout the follow-up period, 1.1% (4/346) of patients experienced extracolonic recurrences at 56.5 (54-73) months after the initial endoscopic resection. Three of these patients (75%) were in the high-risk group and did not undergo salvage treatment. The risk of extracolonic recurrence was significantly higher in the high-risk group compared to the other groups (p = 0.039). CONCLUSION: Physicians should be concerned about the possibility of metastasis during long-term follow-up of high-risk patients and consider salvage treatment.

Fabrication of a monorail-type diagnostic catheter for rescue retrieval technique of a distal embolic protection device.

In this technical report, we describe a challenging case concerning the retrieval of a distal embolic protection device (DEPD) post-carotid artery stenting. We propose a novel rescue retrieval technique for DEPD, employing a fabricated monorail-type HN5 diagnostic catheter. When integrated with existing strategies, this approach may optimize and streamline the process of DEPD removal.

Population-Attributable Risk Fractions for Antiplatelets and Anticoagulants in Spontaneous Intracranial Hemorrhages.

INTRODUCTION: Concerns about spontaneous intracranial hemorrhages (sICHs) have increased over time with the increasing use of antithrombotic agents. Hence, we aimed to analyze the risk and risk fractions for antithrombotics in sICHs in South Korea. METHODS: From the National Health Insurance Service-National Sample Cohort including 1,108,369 citizens, 4,385 cases, aged 20 years or more and newly diagnosed as sICHs between 2003 and 2015, were included in this study. A total of 65,775 sICH-free controls were randomly selected at a ratio of 1:15 from individuals with the same birth year and sex according to a nested case-control study design. RESULTS: Although the incidence rate of sICHs started to decrease from 2007 onward, the use of antiplatelets, anticoagulants, and statins continued to increase. Antiplatelets (adjusted odds ratio [OR] 3.59, 95% confidence interval [CI] 3.18-4.05), anticoagulants (adjusted OR 7.46, 95% CI 4.92-11.32), and statins (adjusted OR 1.98, 95% CI 1.79-2.18) were significant risk factors for sICHs even after adjusting for hypertension, alcohol intake, and cigarette smoking. From 2003-2008 to 2009-2015, the population-attributable fractions changed from 28.0% to 31.3% for hypertension, from 2.0% to 3.2% for antiplatelets, and from 0.5% to 0.9% for anticoagulants. CONCLUSION: Antithrombotic agents are significant risk factors for sICHs, and their contribution is increasing over time in Korea. These findings are expected to draw the attention of clinicians to precautions to be taken when prescribing antithrombotic agents.

Cold snare polypectomy versus cold endoscopic mucosal resection for small colorectal polyps: a multicenter randomized controlled trial.

BACKGROUND: Cold snare polypectomy (CSP) is recommended for the resection of small colorectal polyps. However, few studies have investigated the efficacy of cold endoscopic mucosal resection (cold EMR) for small polyps. Thus, the aim of this study was to investigate the efficacy and safety of cold EMR compared with CSP for small colorectal polyps. METHODS: This was a multicenter, randomized trial conducted in three tertiary centers from January 2018 to February 2021. Patients with polyps sized 6-10 mm were randomized to CSP or cold EMR group. After polypectomy, two additional biopsies were performed to assess the completeness of resection. The primary outcome was complete polyp resection rate. Secondary outcomes were total procedure time and rate of adverse events such as immediate bleeding, delayed bleeding, and perforation. RESULTS: A total of 444 polyps in 327 patients were assessed and randomly assigned to each group. Of those, 425 polyps were finally analyzed based on pathology results. The complete resection rate was not significantly different between cold EMR and CSP groups (91.9% vs 89.8%, p = 0.24). However, the total procedure time was significantly increased in cold EMR (87.6 s vs. 45.8 s, p < 0.001). The rate of polypectomy adverse events was not significantly different between the two groups. No patient had massive bleeding or perforation. CONCLUSIONS: There was no difference in complete resection rate or adverse events between CSP and cold EMR. However, CSP reduced the total procedure time.

Delayed ischemic events with low-dose prasugrel medication for stent-assisted coil embolization in intracranial aneurysm patients.

OBJECTIVE: Much emphasis has been put on the use of antiplatelet medication for the prevention of ischemic events in the treatment of cerebral aneurysms with stent assistance. In this regard, the effectiveness and safety of a low-dose prasugrel regimen during the periprocedural period was recently reported. The purpose of this study was to present the outcomes of patients on low-dose prasugrel regimens during the follow-up period after stent-assisted coil embolization (SACE) of cerebral aneurysms. METHODS: For the 396 consecutive patients undergoing SACE procedures, low-dose prasugrel therapy (5 mg of prasugrel and 100 mg of aspirin) was recommended for 3 months after the endovascular treatment. The authors performed a retrospective review of a single-center experience focusing on delayed ischemic events beyond 1 month after treatment. The mean follow-up period was 24.6 ± 11.3 months. RESULTS: In this cohort of patients on a low-dose prasugrel regimen, cerebral infarction occurred in 1 patient (0.3%, 95% CI 0%-1.8%) beyond 1 month after SACE. No intracranial hemorrhage occurred. Overall ischemic events occurred in 14 patients (3.5%, 95% CI 2.1%-5.9%), all within 6 months of the coiling procedure. All patients had transient symptoms. The events occurred within 2 months after cessation of prasugrel in 11 patients (78.6%). Prasugrel maintenance for 6 months was found to result in lower ischemic events compared with maintenance for 3 months. CONCLUSIONS: For patients undergoing SACE, a low-dose prasugrel regimen was a safe and reliable treatment option for the prevention of delayed ischemic events. Transient ischemic events often occurred within 2 months of stopping prasugrel medication.

n-type charge transport in heavily p-doped polymers.

It is commonly assumed that charge-carrier transport in doped π-conjugated polymers is dominated by one type of charge carrier, either holes or electrons, as determined by the chemistry of the dopant. Here, through Seebeck coefficient and Hall effect measurements, we show that mobile electrons contribute substantially to charge-carrier transport in π-conjugated polymers that are heavily p-doped with strong electron acceptors. Specifically, the Seebeck coefficient of several p-doped polymers changes sign from positive to negative as the concentration of the oxidizing agents FeCl3 or NOBF4 increase, and Hall effect measurements for the same p-doped polymers reveal that electrons become the dominant delocalized charge carriers. Ultraviolet and inverse photoelectron spectroscopy measurements show that doping with oxidizing agents results in elimination of the transport gap at high doping concentrations. This approach of heavy p-type doping is demonstrated to provide a promising route to high-performance n-type organic thermoelectric materials.

Colonoscopy decreases mortality in colorectal cancer patients compared with fecal immunochemical test.

BACKGROUND AND AIM: Colonoscopy and fecal immunochemical test (FIT) are commonly used screening methods for the detection of colorectal cancer (CRC), but their effects on survival have not been compared. We compared survival outcomes in patients with CRC according to the exposure history to colonoscopy or FIT before diagnosis of CRC. METHODS: We performed a nationwide population-based retrospective cohort study using Korean national-insurance claims data. In total, 24 875 patients with CRC diagnosed in 2012 were included. The patients were divided into three groups in terms of examinations performed during the 10 years prior to CRC diagnosis: the colonoscopy group, the FIT group, and the never-screened group. Survival outcomes were compared among the three groups. The colonoscopy group and FIT group were matched using propensity score-matching method. RESULTS: The cohort consisted of 9619 patients in the colonoscopy group, 6936 patients in the FIT group, and 8320 patients in the never-screened group. The 5-year overall survival rates were 74.1% in the colonoscopy group, 65.9% in the FIT group, and 59.6% in the never-screened group (P < 0.001). The adjusted hazard ratios for death were 0.56 (95% confidence interval [CI], 0.53-0.59) in the colonoscopy group and 0.78 (95% CI, 0.74-0.82) in the FIT group compared with the never-screened group. In the matched cohort, the adjusted hazard ratios for death was 0.76 (95% CI, 0.72-0.81) in the colonoscopy group compared with the FIT group. CONCLUSION: Colonoscopy is a more effective method for reducing mortality in patients with CRC compared with FIT.

Association of prediabetes with death and diabetic complications in older adults: the pros and cons of active screening for prediabetes.

BACKGROUND: active screening can improve health outcomes for people with prediabetes. However, its efficacy in older adults remains uncertain. OBJECTIVE: the study aimed to analyse the progression from prediabetes to diabetes in older adults, including associated complications and mortality rates, to determine the benefits of active screening. DESIGN: retrospective cohort study. SETTING: Korean National Health Insurance Service claims database. SUBJECTS: a total of 36,946 adults aged ≥65 years who underwent national health examinations from 2006 to 2008. METHODS: follow-up was until 31 December 2015. Cox's proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for death and diabetic complications. RESULTS: over a median follow-up of 8.2 years, 19.3% of older adults with prediabetes progressed to diabetes. Compared with normoglycaemic adults, the multivariable-adjusted HRs (95% CI) for major adverse cardiovascular events were 1.01 (0.95-1.07), 1.08 (0.95-1.23), 1.14 (1.05-1.23) and 1.50 (1.35-1.68) in adults with prediabetes, newly diagnosed diabetes, diabetes not on insulin and diabetes on insulin, respectively. The corresponding HRs (95% CI) for diabetic retinopathy risk were 1.28 (1.15-1.43), 3.16 (2.71-3.69), 6.58 (6.02-7.19) and 9.17 (8.21-10.24). Diabetic nephropathy risk also significantly increased. CONCLUSIONS: progression from prediabetes to diabetes is an important concern among older adults. Prediabetes is associated with the risk of microvascular complications, but not cardiovascular complications and mortality. Therefore, active regular screening for prediabetes is necessary to prevent microvascular complications.

New Non-Fullerene Acceptor with Extended Conjugation of Cyclopenta [2,1-b:3,4-b'] Dithiophene for Organic Solar Cells.

Herein, we design and characterize 9-heterocyclic ring non-fullerene acceptors (NFAs) with the extended backbone of indacenodithiophene by cyclopenta [2,1-b:3,4-b'] dithiophene (CPDT). The planar conjugated CPDT donor enhances absorption by reducing vibronic transition and charge transport. Developed NFAs with different end groups shows maximum absorption at approximately 790-850 nm in film. Because of the electronegative nature of the end-group, the corresponding acceptors showed deeper LUMO energy levels and red-shifted ultraviolet absorption. We investigate the crystallinity, film morphology, surface energy, and electronic as well as photovoltaic performance. The organic photovoltaic cells using novel NFAs with the halogen end groups fluorine or chlorine demonstrate better charge collection and faster exciton dissociation than photovoltaic cells using NFAs with methyl or lacking a substituent. Photovoltaic devices constructed from m-Me-ITIC with various end groups deliver power conversion efficiencies of 3.6-11.8%.

Correction: CSN6-TRIM21 axis instigates cancer stemness during tumorigenesis.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

CSN6-TRIM21 axis instigates cancer stemness during tumorigenesis.

BACKGROUND: Cancer stem cells (CSCs) are responsible for tumour initiation, metastasis and recurrence. However, the mechanism of CSC formation, maintenance and expansion in colorectal cancer (CRC) remains poorly characterised. METHODS: The role of COP9 signalosome subunit 6 (CSN6) in regulating cancer stemness was evaluated by organoid formation and limited dilution analysis. The role of CSN6-TRIM21-OCT1-ALDH1A1 axis in CSC formation was evaluated in vitro and in vivo. The association of CSN6, TRIM21 and ALDH1A1 expression was validated by a tissue microarray with 267 CRC patients. RESULTS: The results showed that CSN6 is critical for sphere formation and maintaining the growth of patient-derived organoids (PDOs). We characterised the role of CSN6 in regulating cancer stemness, which involves the TRIM21 E3 ubiquitin ligase, transcription factor POU class 2 homeobox 1 (OCT1) and cancer stem cell marker aldehyde dehydrogenase 1 A1 (ALDH1A1). Our data showed that CSN6 facilitates ubiquitin-mediated degradation of TRIM21, which in turn decreases TRIM21-mediated OCT1 ubiquitination and subsequently stabilises OCT1. Consequently, OCT1 stabilisation leads to ALDH1A1expression and promotes cancer stemness. We further showed that the protein expression levels of CSN6, TRIM21 and ALDH1A1 can serve as prognostic markers for human CRC. CONCLUSIONS: In conclusion, we validate a pathway for cancer stemness regulation involving ALDH1A1 levels through the CSN6-TRIM21 axis, which may be utilised as CRC molecular markers and be targeted for therapeutic intervention in cancers.

Stool-Based miR-92a and miR-144* as Noninvasive Biomarkers for Colorectal Cancer Screening.

OBJECTIVES: Current noninvasive screening tests for colorectal cancer (CRC) have insufficient sensitivity. MicroRNA (miRNA) levels in stool have potential as markers for noninvasive screening of CRC. We evaluated the diagnostic value of stool miRNA levels and determined the optimal miRNA subtypes for detecting CRC. METHODS: Stool samples were collected from 29 patients with CRC and 29 healthy controls. The stool levels of miR-21, miR-92a, miR-200c, miR-144*, miR-135a, miR-135b, miR-106a, and miR-17-3p were determined by real-time quantitative reverse transcription polymerase chain reaction. The sensitivity and specificity of the miRNAs for CRC were determined by receiver operating characteristics analysis. RESULTS: Among the eight tested miRNAs, the mean stool levels of miR-21, miR-92a, miR-144*, and miR-17-3p differed significantly between the CRC group and the control group (p =0.014, 0.001, <0.001, and 0.008, respectively). The sensitivities and specificities of miR-21, miR-92, miR-144*, and miR-17-3p were 79.3 and 48.3%, 89.7 and 51.7%, 78.6 and 66.7%, and 67.9 and 70.8%, respectively. In a multivariate analysis, miR-92a and miR-144* were significantly associated with the presence of CRC (p = 0.03 and 0.011, respectively). CONCLUSIONS: The stool levels of miR-92a and miR-144* showed good sensitivity and fair specificity for detection of CRC, and thus may be useful as noninvasive biomarkers for this disease.

Jumbo biopsy forceps versus cold snares for removing diminutive colorectal polyps: a prospective randomized controlled trial.

BACKGROUND AND AIMS: Cold snare polypectomy (CSP) and jumbo forceps polypectomy (JFP) have been shown to be effective for removing diminutive colorectal polyps (DCPs) (≤5 mm). However, no study has compared complete resection rates between CSP and JFP for DCPs. The aim of this study was to compare the efficacy and safety of JFP with CSP for the removal of DCPs. METHODS: This was a prospective randomized controlled trial from 2 tertiary-care referral centers. A total of 1003 patients were screened, and 169 patients with 196 DCPs were enrolled. The main outcome was complete polyp resection rate. RESULTS: Of 196 diminutive polyps, 177 (90.3%) were adenomatous polyps. The overall complete resection rate was 92.1% (163/177). The complete resection rate was not significantly different between JFP and CSP groups (92.0% vs 92.2%; P = .947). JFP achieved complete resection rates comparable with CSP for polyps >3 mm (90.3% vs 89.8%; P = .928). Polypectomy procedure time, tissue retrieval rate, and rate of postpolypectomy adverse events were not significantly different between the 2 groups. CONCLUSIONS: Both JFP and CSP achieved complete resection rates of >90% for DCPs. Thus, JFP may be considered for polypectomy of DCPs. (International clinical trial registry number: KCT0002805.).

Diagnostic value of magnetic resonance cholangiopancreatography to detect bile duct stones in acute biliary pancreatitis.

OBJECTIVES: This study aims to evaluate the diagnostic value of magnetic resonance cholangiopancreatography (MRCP) in detecting common bile duct (CBD) stones in acute biliary pancreatitis (ABP). METHODS: The medical records of patients presenting with ABP from January 2008 to July 2013 were reviewed to assess the value of MRCP in detecting CBD stones in ABP. Endoscopic retrograde cholangiopancreatography (ERCP) was used as the reference standard to assess the diagnostic yield of MRCP in detecting choledocholithiasis. When ERCP was unavailable, intraoperative cholangiography or clinical follow-up was used as the reference standard. RESULTS: Seventy-eight patients who underwent MRCP were diagnosed with ABP, and thirty of the 78 patients (38%) were confirmed to have CBD stones per the study protocol. The sensitivity of MRCP in detecting CBD stones in ABP was 93.3% compared to 66.7% for abdominal CT (P < 0.008). The overall accuracy of MRCP in detecting choledocholithiasis was 85.9% compared to 74.0% for abdominal CT (P < 0.041). The area under the receiver operating characteristic curve (AUC) of MRCP in detecting CBD stones was 0.882, which was more accurate than the AUC of 0.727 for abdominal CT (P = 0.039). In 38 patients who underwent ERCP, the sensitivity and negative predictive value of MRCP in detecting CBD stones were both 100% regardless of the dilatation of the bile duct (≥7 mm versus < 7 mm). CONCLUSION: MRCP is an effective, noninvasive modality to detect CBD stones in ABP and can help identify patients who require ERCP.

Treatment of benign perforations and leaks of the esophagus: factors associated with success after stent placement.

BACKGROUND: Self-expanding metal stent (SEMS) is effective and safe for the treatment of benign esophageal perforations or leaks. The purpose of this study was to identify factors associated with clinical success after SEMS placement. METHODS: Patients who received SEMS placement for treatment of benign esophageal perforations or leaks were retrospectively identified. These patients were analyzed for factors associated with clinical success and complications. RESULTS: A total of 31 patients underwent stent insertion for benign esophageal perforations (n = 11) or anastomotic leaks (n = 20). Clinical success was achieved in twenty-three patients (74.2%) after initial stent insertion. In multivariate analysis, early stent insertion within 1 day was identified as a significant independent predictor of successful sealing (Odds ratio = 3.14, 95% CI 1.36-7.24; p = 0.013). The anastomotic leak group needed a longer stent dwelling time (≥ 4 weeks) compared to the perforation group (75.0% vs. 27.3%, p = 0.022). CONCLUSIONS: Clinical success was significantly associated with early stent insertion. The dwelling time of stent was shorter for benign perforations compared to anastomotic leaks.

Effect of scapular stabilization exercise on neck alignment and muscle activity in patients with forward head posture.

[Purpose] The purpose of this study was to investigate the effects of scapula movement on neck alignment and the muscles in patients with forward head posture, who has the structural changes around the neck caused from the forward head posture, when scapular stabilization exercise is applied. [Subjects and Methods] A sample of 30 patients with forward head posture were recruited and participated in an intervention for 30 minutes a day, three times per week for 4 weeks. Fifteen patients were assigned to the scapular stabilization exercise group and the remaining 15 were assigned to the neck stabilization exercise group. Before the intervention, the craniovertebral angle (CVA), cranial rotation angle (CRA), and muscle activity of the muscles around the neck were measured. Four weeks later, these 3 factors were re-measured and analyzed. [Results] Within-group changes in CVA and CRA were observed in both groups and were statistically significant. Only the CVA group had a statistically significant between-group differences. Within-group changes in muscular activity were significant differences in all groups. Between groups, the lower back trapezius and serratus anterior showed statistically significant differences. [Conclusion] Scapular stabilization brought about improvement in posture through activation of the neck muscles, the lower trapezius, and the serratus anterior. Therefore, the intervention has a positive effect on neck alignment by reducing the compensatory movements of the muscles involved in forward head posture. Structural changes are observed.

Effects on muscle activities according to the type of bodyblade exercise in quadruped position.

[Purpose] Most studies on bodyblade exercise have examined changes in muscle activities in the trunk and shoulders according to the hand position or direction while in a standing position. The present study compared and examined the changes in muscle activities around the shoulders and trunk according to different bodyblade lifting methods during stabilization exercise in a quadruped position. [Subjects and Methods] The present study was conducted on 20 healthy males. The following exercise four types were performed with the bodyblade held by flexing the dominant arm at 180° in a quadruped position. The muscle activity and the ratio of muscle activity were measured. [Results] The SA and IO, EO muscles showed significant differences. Moreover, the SA/UT activity ratio showed significant differences according to the type of exercise. The Tukey's post hoc test results were as follows: for the SA muscle, exercise types 4, 2 were more effective than types 1, 3: and for the IO muscle, types 1, 2 were more effective than types 3, 4. [Conclusion] The present study showed that type 2 scapular stabilization exercise (crossed leg lifting with the hand raised above the head on a vertical plane) showed selective and positive effects on trunk muscle strengthening and stabilization. In future, additional studies are required to design effective exercise programs for pain management and improvement of muscle activities in patients with complaints of shoulder pain due to scapular winging.

Effects of dynamic neural mobilization on cerebral cortical activity in patients with stroke.

[Purpose] The current study aimed to identify the effects of dynamic neural mobilization on cerebral cortical activity in patients with stroke, and to present efficient intervention methods for stroke management. [Subjects and Methods] A total of 20 hemiplegic patients diagnosed with stroke over the past 6 months were sampled, and randomly divided into groups I (n=10) and II (n=10). Groups I and II underwent neural mobilization and dynamic neural mobilization, respectively, on the paralyzed arm. Both interventions were administered for 30 min, once a day, for 4 days a week, over a course of 4 weeks. ß-waves and µ-rhythms in the C3 and C4 areas of the cerebral cortex were measured using electroencephalography, both before and after the intervention. [Results] After the intervention, both groups showed significant changes in the ß-waves and µ-rhythms in the C3 area alone. Further, significant inter-group differences in the ß-waves and µ-rhythms were only present in the C3 area. [Conclusion] Dynamic neural mobilization is an efficient intervention because it increases ß-waves and µ-rhythms in the cerebral cortex. Therefore, the effects of continuous intervention programs involving dynamic neural mobilization in patients with stroke should be investigated in the future.

Effect of lumbar stabilization exercise on disc herniation index, sacral angle, and functional improvement in patients with lumbar disc herniation.

[Purpose] This study aimed to examine the effects of pelvic movements on the back function of patients with lumbar disc herniation when lumbar stabilization exercise was applied to the patients, suggest an intervention method that can be used in future clinical therapies. [Subjects and Methods] Thirty patients with lumbar disc herniation underwent the intervention 30 minutes per day, three times per week for 4 weeks. Of them, 15 patients were assigned to the balance center stabilization resistance exercise group (experimental group I) and the other 15 were assigned to the three-dimensional stabilization exercise group (experimental group II). Before the intervention, disc herniation index was measured using magnetic resonance imaging, sacral angle was measured using X-ray, and back function was measured using the KODI. Four weeks later, these three factors were re-measured and analyzed. [Results] There was a significant pre- versus post-intervention difference in disc herniation index, sacral angle, and KODI in experimental group I and a significant difference in disc herniation index and KODI in experimental group II, and each group of disc herniation index and sacral angle had a significant difference. In experimental group I, each disc herniation index and sacral angle had a negative correlation. [Conclusion] The lumbar stabilization exercise, which controls balance using pelvic movements, improves mobility and stability of the sacroiliac joint; therefore, it increases pelvic and back movements. These kinds of movements not only improved proprioception sense, they also had positive effects on lumbar disc function recovery.

Analysis of Aggregation Delay for Multisource Sensor Data with On-Off Traffic Pattern in Wireless Body Area Networks.

Data aggregation plays an important role to improve the transmission efficiency in wireless body area networks (WBANs); however, it inherently induces additional aggregation delay. Therefore, the effect of packet aggregation on WBAN applications, which are vulnerable to delay, must be analyzed rigorously. In this paper, we analyze the packet aggregation delay for multisource sensor data with an on-off traffic pattern in WBANs. Considering two operational parameters of the aggregation threshold and aggregation timer, we calculate the probability that a packet aggregation occurs during a unit time and then derive the average aggregation delay in closed-form. The analysis results show that the aggregation delay increases as the aggregation timer or aggregation threshold increases, but is bounded below a certain level according to the number of active sensors and their on-off traffic attribute. This implies that the data aggregation technique can maximize the transmission efficiency while satisfying a given delay requirement in the WBAN system.