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Introduction: Although tumor size (TS) is known to affect surgical outcomes in laparoscopic liver resection (LLR), its impact on laparoscopic major hepatectomy (L-MH) is not well studied. The objectives of this study were to investigate the impact of TS on the perioperative outcomes of L-MH and to elucidate the optimal TS cutoff for stratifying the difficulty of L-MH., Methods: This was a post-hoc analysis of 3008 patients who underwent L-MH at 48 international centers. A total 1396 patients met study criteria and were included. The impact of TS cutoffs was investigated by stratifying TS at each 10-mm interval. The optimal cutoffs were determined taking into consideration the number of endpoints which showed a statistically significant split around the cut-points of interest and the magnitude of relative risk after correction for multiple risk factors., Results: We identified 2 optimal TS cutoffs, 50 mm and 100 mm, which segregated L-MH into 3 groups. An increasing TS across these 3 groups (≤ 50 mm, 51-100 mm, > 100 mm), was significantly associated with a higher open conversion rate (11.2%, 14.7%, 23.0%, P < 0.001), longer operating time (median, 340 min, 346 min, 365 min, P = 0.025), increased blood loss (median, 300 ml,  ml, 400 ml, P = 0.002) and higher rate of intraoperative blood transfusion (13.1%, 15.9%, 27.6%, P < 0.001). Postoperative outcomes such as overall morbidity, major morbidity, and length of stay were comparable across the three groups., Conclusion: Increasing TS was associated with poorer intraoperative but not postoperative outcomes after L-MH. We determined 2 TS cutoffs (50 mm and 10 mm) which could optimally stratify the surgical difficulty of L-MH., (© 2023. Society of Surgical Oncology.)

Introduction: Despite the advances in minimally invasive (MI) liver surgery, most major hepatectomies (MHs) continue to be performed by open surgery. This study aimed to evaluate the risk factors and outcomes of open conversion during MI MH, including the impact of the type of approach (laparoscopic vs. robotic) on the occurrence and outcomes of conversions., Methods: Data on 3880 MI conventional and technical (right anterior and posterior sectionectomies) MHs were retrospectively collected. Risk factors and perioperative outcomes of open conversion were analyzed. Multivariate analysis, propensity score matching, and inverse probability treatment weighting analysis were performed to control for confounding factors., Results: Overall, 3211 laparoscopic MHs (LMHs) and 669 robotic MHs (RMHs) were included, of which 399 (10.28%) had an open conversion. Multivariate analyses demonstrated that male sex, laparoscopic approach, cirrhosis, previous abdominal surgery, concomitant other surgery, American Society of Anesthesiologists (ASA) score 3/4, larger tumor size, conventional MH, and Institut Mutualiste Montsouris classification III procedures were associated with an increased risk of conversion. After matching, patients requiring open conversion had poorer outcomes compared with non-converted cases, as evidenced by the increased operation time, blood transfusion rate, blood loss, hospital stay, postoperative morbidity/major morbidity and 30/90-day mortality. Although RMH showed a decreased risk of conversion compared with LMH, converted RMH showed increased blood loss, blood transfusion rate, postoperative major morbidity and 30/90-day mortality compared with converted LMH., Conclusions: Multiple risk factors are associated with conversion. Converted cases, especially those due to intraoperative bleeding, have unfavorable outcomes. Robotic assistance seemed to increase the feasibility of the MI approach, but converted robotic procedures showed inferior outcomes compared with converted laparoscopic procedures., (© 2023. Society of Surgical Oncology.)

Background: Tumors involving the hepatic veins at the hepatocaval confluence often require major or extended hepatectomies. Color Doppler intraoperative ultrasonography (CD-IOUS) evaluation of liver hemodynamics to assess congestion in the veno-occlusive parenchyma provides real-time information helpful in parenchyma-sparing surgery (PSS). This study evaluated the feasibility of CD-IOUS in patients undergoing laparoscopic liver resections for such tumors and its capacity to allow PSS., Methods: Consecutive patients undergoing laparoscopic liver resection for tumors at the hepatocaval confluence requiring resection of at least one hepatic vein between January 2010 and August 2020 were included. Patients were divided in 3 groups: (A) patients not assessed with CD-IOUS because it would not change the scheduled operation; patients assessed with CD-IOUS and treated with (B) PSS and (C) no-PSS. Portal blood flow in the veno-occlusive parenchyma was assessed using CD-IOUS at baseline and after clamping the concerned hepatic vein., Results: The study included 43 out of 47 patients with tumors at the hepatocaval confluence. There were 19 patients in group A. Among patients assessed with CD-IOUS, the resection of 26 hepatic veins was planned: 25 were resected, and 1 was spared. Group B included 22 patients treated with PSS, whereas group C included 2 patients with resection of all veno-occlusive parenchyma. No postoperative mortality or major morbidity was observed. The median length of hospital stay was 5 days., Conclusions: Selected patients with tumors involving the hepatocaval confluence can be safely approached using laparoscopy. CD-IOUS evaluation of the veno-occlusive area can increase the success rate of PSS., (© 2022. The Society for Surgery of the Alimentary Tract.)

Background: Laparoscopic segment 7 segmentectomy and segment 6-7 bisegmentectomy are challenging resections because of the posterior position and the lack of landmarks. The anatomy of the right posterior Glissonean pedicle and the caudal view of laparoscopy make such resections suitable for the Glissonean pedicle-first approach., Methods: The study population included all consecutive patients treated with laparoscopic liver resection from August 2019 to February 2020. The approach is based on the ultrasonographic identification of the right posterior or segmental pedicle from the dorsal side of the liver after complete mobilization. The pedicle of interest is isolated through mini-hepatotomy and clamped. The segment anatomy is defined by ischemia. The transection starts from the ventral side, close to the right hepatic vein that is exposed and followed craniocaudally., Results: Ten patients underwent anatomical laparoscopic resection of right posterolateral segments. There were 7 colorectal liver metastases, 2 hepatocellular carcinoma, and 1 biliary cysto-adenoma. Five patients underwent Sg7 resection, one patient underwent a Sg7 subsegmentectomy, and 4 underwent Sg6-7 bisegmentectomy. The Glissonean pedicle-first approach was feasible in eight patients. The craniocaudal approach to the RHV was feasible in six patients, not indicated in three cases and was abandoned in one patient for technical difficulty. There was no operative morbidity or mortality. Median post-operative hospital stay was 5 days., Conclusions: The Glissonean pedicle-first approach is safe and effective for laparoscopic anatomic resections of the right posterior sector. The craniocaudal approach to right hepatic vein from the ventral side is a convenient procedure to follow the segmental anatomy deep in the parenchyma.

Intraoperative liver ultrasound has a crucial role to guide open liver surgery. A 4-step ultrasound liver map technique for laparoscopic liver resection (LLR) has been standardized in our center. The aim of this study was to evaluate outcomes of our technique according to the hepatectomy technical complexity. A difficulty scale (DS) ranging from 1 to 10 was applied to each LLR. A cumulative sum control-chart analysis identified 3 periods of gradually increasing DS. Perioperative outcomes of the 3 periods were compared. 300 LLRs performed between 2006 and 2018 were analyzed. Median DS was 3 for first 100 cases (P1), 5 for cases 101-200 (P2) and 6 for cases 201-300 (P3). A significantly greater percentage of postero-superior segments resections (P1 11%, P2 36%, P3 46%, p < 0.001) were performed in P3. P3 LLRs had a significantly longer transection time (p < 0.001) and wider cut surface area (p < 0.001), but median blood losses were similar among the 3 periods (P1 100 cc, P2 100 cc, P3 140 cc). There were no differences among periods in overall morbidity (P1 12%, P2 17%, P3 17%), major morbidity (P1 1%, P2 2%, P3 3%) and length of hospital stay (5 days in all the three groups). Despite the increasing surgical complexity of LLR, ultrasound liver map technique allows good perioperative outcomes.

Background: The albumin-indocyanine green evaluation (ALICE) model based on serum albumin and indocyanine retention rate has been shown to be an effective method for predicting postoperative outcomes in hepatocellular carcinoma patients. Aim of the study was to validate the ALICE model in a large Western cohort of patients by comparing the albumin-bilirubin (ALBI) score and Child-Turcotte-Pugh (CTP) score., Methods: A total of 400 patients who underwent hepatic resection from January 2005 to June 2016 at three centers were enrolled. The ALICE, ALBI, and CTP scores were computed for all patients., Results: The ALICE score correlated better with ALBI (r = 0.428) than with CTP score (r = 0.302). Both the ALICE (grade 1: 49%; grade 2: 51%) and the ALBI (grade 1: 52.5%; grade 2: 47.5%) scores stratified the CTP class A patients into two distinct classes. The incidence of ascites (grades 1-3: ALICE 11%, 20%, 58%; ALBI 11%, 23%, 50%) and severe liver failure (ALICE 8.7%, 10.5%, 41.7%; ALBI 8.6%, 12%, 50%) increased with increasing ALBI and ALICE grade and were similar for the same grade., Conclusions: The ALICE model can assess hepatic functional reserve and predict postoperative outcomes with efficacy comparable with the ALBI grade and better than the CTP score., (© 2018 Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

Background: The highest mortality rates after liver surgery are reported in patients who undergo resection for hilar cholangiocarcinoma (HCCA). In these patients, postoperative death usually follows the development of hepatic insufficiency. We sought to determine the factors associated with postoperative hepatic insufficiency and death due to liver failure in patients undergoing hepatectomy for HCCA., Study Design: This study included all consecutive patients who underwent hepatectomy with curative intent for HCCA at 2 centers, from 1996 through 2013. Preoperative clinical and operative data were analyzed to identify independent determinants of hepatic insufficiency and liver failure-related death., Results: The study included 133 patients with right or left major (n = 67) or extended (n = 66) hepatectomy. Preoperative biliary drainage was performed in 98 patients and was complicated by cholangitis in 40 cases. In all these patients, cholangitis was controlled before surgery. Major (Dindo III to IV) postoperative complications occurred in 73 patients (55%), with 29 suffering from hepatic insufficiency. Fifteen patients (11%) died within 90 days after surgery, 10 of them from liver failure. On multivariate analysis, predictors of postoperative hepatic insufficiency (all p < 0.05) were preoperative cholangitis (odds ratio [OR] 3.2), future liver remnant (FLR) volume < 30% (OR 3.5), preoperative total bilirubin level >3 mg/dL (OR 4), and albumin level < 3.5 mg/dL (OR 3.3). Only preoperative cholangitis (OR 7.5, p = 0.016) and FLR volume < 30% (OR 7.2, p = 0.019) predicted postoperative liver failure-related death., Conclusions: Preoperative cholangitis and insufficient FLR volume are major determinants of hepatic insufficiency and postoperative liver failure-related death. Given the association between biliary drainage and cholangitis, the preoperative approach to patients with HCCA should be optimized to minimize the risk of cholangitis., (Copyright © 2016 American College of Surgeons. Published by Elsevier Inc. All rights reserved.)

Background: The aim of the study was to assess the capacity of indocyanine green retention test at 15 min (ICGR15) to predict chemotherapeutic-associated liver injuries (CALI)., Methods: Patients undergoing liver resection for CLM that received preoperative oxaliplatin and/or irintecan-based chemotherapy within 3 months before surgery and scheduled first hepatectomy were considered., Results: 166 out of 983 patients treated between 01/2001 and 04/2014 fulfilled the inclusion criteria. The median number of cycles of preoperative chemotherapy was 6.0 ± 4.87. Chemotherapy was mainly based on oxaliplatin in 123 (74.1%). Bevacizumab was associated in 51(31%) patients. A total of 102 (61.4%) patients had at least 1 CALI. Grade 2-3 steatosis occurred in 56 (33.7%) patients and steatohepatitis in19(11.5%). Sinusoidal obstructive syndrome (SOS) was presented in 93 (56%) patients. 23(13.8%) patients had nodular regeneration hyperplasia. At multivariate analysis the only predictive factor of ICGR≥10% was age≥65 years (p = 0.001). A median split (ICGR15 = 8%) was used to categorized ICGR15 value. Multivariate analysis showed that age≥ 65 [OR 2.530 (CI95% 1.28-4.97) p < 0.001], male sex [OR 2.614 (CI95% 1.31-5.20) p < 0.001], SOS [OR 1.954 (CI95% 1.00-3.81) p = 0.050] and administration of Bevacizumab [OR 2.201 (CI95% 1.07-4.50) p = 0.031] were predictive factors for ICGR≥8%., Conclusions: ICGR15 test can predict the diagnosis of SOS. High ICGR15 value is more common in elderly male patients and after bevacizumab administration., (Copyright © 2016 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.)

Background: Despite extensive preoperative evaluation, a significant proportion of patients with biliary cancer (BC) proves to be unresectable at laparotomy. Diagnostic laparoscopy (DL) has been suggested to avoid unnecessary laparotomy. Aim of the study was to evaluate the additional benefit of combining LUS to DL in patients with proximal BC., Methods: Inclusion criteria were all patients affected by proximal BC undergone DL + LUS based on the following criteria: preoperative diagnosis of gallbladder cancer, hilar cholangiocarcinomas (HC) and borderline resectable intrahepatic cholangiocarcinoma (IHC). The overall yield (OY) and accuracy (AC) of DL ± LUS in determining unresectable disease were calculated., Results: From 01/2006 to 12/2014, 107 out of 191 (56%) potentially resectable proximal BC were evaluated. One hundred patients fulfilled inclusion criteria: 44 IHC, 21 GC and 35 HC. Forty-eight (48%) patients were male with median age of 65 (41-87) years. The median number of preoperative imaging was 3 ± 0.99. Patients underwent DL + LUS 10.5 ± 15.6 days after last imaging. DL + LUS identified unresectable diseases in 24 patients, 6 (25%) of them only thanks to LUS findings (3 GC and 3 IHC). At laparotomy, 6 (4 HC and 2 GC) out of 76 patients were found unresectable because of carcinomatosis (n = 2), new liver metastasis (n = 2) and vascular invasion (n = 2). LUS increased the OY (from 18 to 24%) and AC (from 60 to 80%) in the whole group. The advantages of LUS were confirmed for GC (OY from 38.1 to 52.4%, AC from 61.5 to 84.6%) and IHC patients (OY from 11.4 to 18.2%, AC from 62.5 to 100%) but not for HC group. The presence of biliary drainage was the only factor able to predict negative yield (p < 0.001)., Conclusions: LUS increases overall yield and accuracy of DL for detecting unresectable disease in patients with preoperative diagnosis of gallbladder cancer and borderline resectable intrahepatic cholangiocarcinomas.

Background: Outcomes in obese patients who underwent liver resection have been analyzed, but series are heterogeneous and data are controversial. The aim of this study was to analyze short-outcome in obese patients undergone hepatectomy for colorectal metastases., Study Design: A retrospective analysis on 1,021 consecutive hepatectomies between January 2000 and April 2014 for colorectal metastases was carried out. World Health Organization Classification of obesity (body mass index >30 kg/m(2)) was used to identify 140 obese patients. Outcomes were compared among obese and nonobese patients., Results: Obese patients were mainly male (78%) and were associated more frequently with hypertension (51% vs 29%, P < .001), ischemic heart disease (9% vs 3%, P = .007), and diabetes (23% vs 10%, P < .001) compared with nonobese patients. Approximately 30% of patients underwent major hepatectomy in the 2 groups. Associated resections were performed in 36% of obese and 37% of nonobese patients. Median parenchymal transection time (80 ± 64 minutes vs 70 ± 50 minutes, P = .013) and blood loss (300 ± 420 vs 200 ± 282, P = .001) were greater in obese patients. Postoperative mortality was nil in obese patients and 0.6% in nonobese patients. Overall morbidity was greater in obese patients (41% vs 31%, P = .012) mainly related to pulmonary complications (16% vs 9%, P = .012). Reinterventions were more frequent in obese patients (3.6% vs 1.2%, P = .004). Median hospital stay was comparable. At pathologic examination, hepatic steatosis was greater in obese (69% vs 43%, P < .001). At multivariate analysis, age >65 years (odds ratio [OR] 1.43, 95% confidence interval [95% CI] 1.09-1.88), obesity (OR 1.64, 95% CI 1.13-2.38), major hepatectomies (OR 1.65, 95% CI 1.31-2.33), and associated resections (OR 1.67, I95% CI 1.27-2.20) were independent predictors of overall morbidity (P < .001). Among obese patients, there was a positive correlation between age and severity of complications (R = 0.173, P = .041)., Conclusion: Obese patients undergoing hepatectomy for colorectal metastases should be approached with caution because of an increased risk of postoperative morbidity., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Laparoscopic liver surgery has gained widespread acceptance and nowadays it is suggested even for malignant disease. Although the benefits on short-term outcomes have been proven, data on oncological safety are still lacking. The aim of this study is to assess oncologic results after ultrasound-guided laparoscopic liver resection (LLR) or open liver resection (OLR) for colorectal metastases. 37 consecutive patients undergoing LLR between 01/2004 and 03/2014 were matched at a ratio of 1:1 with 37 OLR. Matching criteria were male sex, number and diameter of liver metastases, segment location, synchronous presentation, site and stage of primary tumor, positive lymph nodes of the primary, and concomitant extrahepatic disease. Demographic characteristics were similar among groups. Parenchymal transection time was longer in the LLR group (68 ± 38.2 SD vs 40 ± 33.7 SD, p = 0.01). Mortality was nil in LLR and OLR. Overall morbidity was significantly lower in LLR (13.5 vs 37.8%, p = 0.02), although severe complications were similar among the two groups. Patients undergoing LLR were discharged earlier (5 ± 2.3 SD vs 8 ± 6.6 SD days, p < 0.001). The median margin width was 5 (0-40) mm in LLR vs 8 (0-25) mm in OLR, p = 0.897. R1 resection was recorded in four LLR and three OLR (p = 1). Overall recurrences were similar among groups. Eight patients with hepatic or extrahepatic recurrence among LLR underwent surgery vs four of OLR (p = 0.03). After a median follow-up of 35.7 months in LLR and 47.9 months in OLR, 3-year overall survival was 91.8% LLR and 74.8% OLR (p = 0.14). 3-year disease-free survival was 69.1% LLR and 65.9% OLR (p = 0.53). Multivariate analysis showed that postoperative complications [HR 3.42 (95% CI 1.32-8.89)] and multiple metastases [HR 3.84 (95% CI 1.34-10.83)] were independent predictors of worse survival (p = 0.01). Ultrasound-LLR for colorectal hepatic metastases is safe, ensuring oncologic outcomes comparable to OLR.

Background: Intraoperative liver ultrasound has an established role in liver surgery to complete staging and to guide resection. The same performances should be expected by laparoscopic ultrasound (LUS)., Methods: LUS is first performed to identify relationships between tumor and vasculo-biliary pedicles. The planes where the main vascular structures run are marked on the liver surface. Parenchymal transection is performed and each vessel recognized during LUS exploration is divided., Results: From 01/2009 to 10/2013, in 61 out of 742 liver resections (8.2 %), a laparoscopic approach was attempted. The conversion rate was 9.8 % (six patients). No conversion was related to bleeding or intraoperative complications. The remnant 55 patients were affected by benign lesions in 11 cases and malignant tumors in 44. The resections included 3 left hepatectomies, 14 bisegmentectomies Sg2-3, 5 segmentectomies, and 38 wedge resections. Associated procedures were performed in eight patients (14.5 %), including four colorectal resections. Median duration of surgery was 150 min (60-345 min). Median operative blood loss was 100 mL (0-500 mL). Median size of resected tumor was 2.5 cm (0.9-8 cm). Median surgical margin in oncological resections was 7 mm (0-50 mm). Postoperative complications occurred in four patients (7.2 %), all grade 2 according to Dindo classification. No liver-related morbidity occurred. Median length of hospital stay was 5 days (3-9 days)., Conclusions: Ultrasound-guided liver resections can be performed by laparoscopic approach with the same accuracy than open surgery.

Objectives: To compare outcomes following liver resection of colorectal metastases (CRLM) from mucinous adenocarcinoma (Muc-CRLM) versus nonmucinous adenocarcinoma (non-Muc-CRLM)., Background: Among colorectal adenocarcinomas, 10%-15% are mucinous and have worse prognoses than nonmucinous ones. Outcomes of liver resection for Muc-CRLM remain unknown., Methods: Among 701 patients undergoing liver resection for CRLM between 1998 and 2012, 102 (14.6%) had Muc-CRLM. Each was matched with a non-Muc-CRLM patient, based on tumor N status, disease-free interval (DFI) between primary tumor and metastases, CRLM number and diameter, extrahepatic disease, and preoperative chemotherapy., Results: Within the 2 groups, 69.6% of patients had N+ primary tumor, 72.5% had DFI of less than 12 months, 28.4% had 4 or more CRLM, and 22.5% had associated extrahepatic disease. 59.8% of patients received preoperative chemotherapy. Muc-CRLM patients had higher prevalences of right/transverse colon cancer (55.9% vs 29.4%; P<0.0001) and K-ras mutation (67 patients tested, 61.8% vs 36.4%; P=0.037), as well as lower response to preoperative chemotherapy (63.9% vs 85.2%; P=0.006). Multivariate analysis showed Muc-CRLM to have lower rates of 5-year overall (33.2% vs 55.2%; P=0.010) and disease-free survival (32.5% vs 49.3%; P=0.037). Muc-CRLM recurrence was more often peritoneal (20.3% vs 6.5%; P=0.024) and at multiple sites (47.5% vs 21.0%; P=0.002), and had lower rates of re-resection (16.9% vs 43.5%; P=0.002) and 3-year post-recurrence survival (11.7% vs 43.4%; P=0.0003)., Conclusions: Muc-CRLM patients strongly differed from non-Muc-CRLM patients, showing a lower chemotherapy response and higher K-ras mutation prevalence. Muc-CRLM appears to be a separate disease, which is associated with worse survival and aggressive rarely re-resectable recurrences.

The aim of this study was to determine potential relationships between anthropometric parameters and athletic performance with special consideration to repeated-sprint ability (RSA). Sixteen players of the senior male Qatar national soccer team performed a series of anthropometric and physical tests including countermovement jumps without (CMJ) and with free arms (CMJwA), straight-line 20 m sprint, RSA (6 × 35 m with 10 s recovery) and incremental field test. Significant (P < 0.05) relationships occurred between muscle-to-bone ratio and both CMJs height (r ranging from 0.56 to 0.69) as well as with all RSA-related variables (r < -0.53 for sprinting times and r = 0.54 for maximal sprinting speed) with the exception of the sprint decrement score (Sdec). The sum of six skinfolds and adipose mass index were largely correlated with Sdec (r = 0.68, P < 0.01 and r = 0.55, P < 0.05, respectively) but not with total time (TT, r = 0.44 and 0.33, P > 0.05, respectively) or any standard athletic tests. Multiple regression analyses indicated that muscular cross-sectional area for mid-thigh, adipose index, straight-line 20 m time, maximal sprinting speed and CMJwA are the strongest predictors of Sdec (r(2) = 0.89) and TT (r(2) = 0.95) during our RSA test. In the Qatar national soccer team, players' power-related qualities and RSA are associated with a high muscular profile and a low adiposity. This supports the relevance of explosive power for the soccer players and the larger importance of neuromuscular qualities determining the RSA.

Aim: Many studies have indicated that lymph node metastases and the depth of invasion of the primary tumor are the most reliable prognostic factors for patients with radically resected gastric cancer. Recently the ratio between metastatic and examined lymph nodes (n ratio) has been proposed as a new prognostic indicator. The aim of this study was to evaluate the prognostic value of n ratio in patients with gastric cancer., Methods: We retrospectively reviewed the data of 399 patients who had undergone radical resection for gastric carcinoma., Results: N ratio was significantly greater in patients with large and undifferentiated tumors. Moreover, it was significantly related to both the number and location of lymph node metastases. Survival curves showed that n ratio was strictly related to patients' survival. Multivariate analysis confirmed that it was an important independent prognostic indicator., Conclusion: N ratio is useful to better evaluate the status of lymph node metastases in patients with gastric cancer submitted to radical surgery. Moreover it is a very important independent prognostic factor for gastric cancer.

Objectives: To quantify the relationships between age, sex and country of residence and sleep time (time in bed) in young people aged 9-18 years., Methods: Thirty studies of sleep patterns in healthy adolescents from the last 30 years in 20 countries were reviewed. Monte Carlo simulation generated pseudo-data where only summary statistics were available. Raw and pseudo-data were combined, generating a total of 92,977 data points. A mixed model, clustering on countries, analysed data for school and non-school days separately., Results: Sleep time varied with sex, age and geographical region. School day sleep differed slightly between boys and girls, girls sleeping 11 min/night more than boys (p = 0.003). On non-school days, girls slept 29 min more each day (p = 0.003). Sleep time declined with age, - 14 min/day per year of age (school days), and seven min/night per year of age (non-school days). Large differences between countries, showed adolescents from Asian countries sleeping 40-60 min less each night than Americans, and 60-120 min less than Europeans., Conclusion: Sex, age, geographical region and day type interact and predict sleep patterns in adolescents. One consistent trend is the increasing gap between sleep on school days and non-school days as adolescents get older., (Copyright © 2009 Elsevier Ltd. All rights reserved.)