Machine learning versus logistic regression for the prediction of complications after pancreatoduodenectomy.

BACKGROUND: Machine learning is increasingly advocated to develop prediction models for postoperative complications. It is, however, unclear if machine learning is superior to logistic regression when using structured clinical data. Postoperative pancreatic fistula and delayed gastric emptying are the two most common complications with the biggest impact on patient condition and length of hospital stay after pancreatoduodenectomy. This study aimed to compare the performance of machine learning and logistic regression in predicting pancreatic fistula and delayed gastric emptying after pancreatoduodenectomy. METHODS: This retrospective observational study used nationwide data from 16 centers in the Dutch Pancreatic Cancer Audit between January 2014 and January 2021. The area under the curve of a machine learning and logistic regression model for clinically relevant postoperative pancreatic fistula and delayed gastric emptying were compared. RESULTS: Overall, 799 (16.3%) patients developed a postoperative pancreatic fistula, and 943 developed (19.2%) delayed gastric emptying. For postoperative pancreatic fistula, the area under the curve of the machine learning model was 0.74, and the area under the curve of the logistic regression model was 0.73. For delayed gastric emptying, the area under the curve of the machine learning model and logistic regression was 0.59. CONCLUSION: Machine learning did not outperform logistic regression modeling in predicting postoperative complications after pancreatoduodenectomy.

The effect of anastomotic leakage on the incidence of recurrence after tri-modality therapy for esophageal adenocarcinomas.

BACKGROUND: Neoadjuvant chemoradiotherapy (nCRTx) reduces the incidence of recurrence, while anastomotic leakage has shown increase the risk of recurrence. The primary objective of this retrospective study was to investigate the incidence and pattern of recurrence and secondary median recurrence-free interval and post-recurrence survival in patients with and without anastomotic leakage after multimodal therapy for esophageal adenocarcinoma. METHODS: Patients with recurrence after multimodal therapy between 2010 and 2018 were included. RESULTS: Six hundred and eighteen patients were included, 91 (14.7%) had leakage and 278 (45.0%) recurrence. Patients with leakage did not develop recurrence more often (48.4%) than those without (44.4%, [p = 0.484]). Recurrence-free interval for patients with (n = 44) and without leakage (n = 234) was 39 and 52 weeks, respectively (p = 0.049). Post-recurrence survival was 11 and 16 weeks, respectively (p = 0.702). Specified by recurrence site, post-recurrence survival for loco-regional recurrences was 27 versus 33 weeks (p = 0.387) for patients with and without leakage, for distant 9 versus 13 (p = 0.999), and for combined 11 versus 18 weeks (p = 0.492). CONCLUSION AND DISCUSSION: No higher incidence of recurrent disease was observed in patients with anastomotic leakage, however it is associated with a shorter recurrence-free interval. This could have implications for surveillance, as early detection of recurrent disease could influence therapeutic options.

Machine learning models in clinical practice for the prediction of postoperative complications after major abdominal surgery.

Complications after surgery have a major impact on short- and long-term outcomes, and decades of technological advancement have not yet led to the eradication of their risk. The accurate prediction of complications, recently enhanced by the development of machine learning algorithms, has the potential to completely reshape surgical patient management. In this paper, we reflect on multiple issues facing the implementation of machine learning, from the development to the actual implementation of machine learning models in daily clinical practice, providing suggestions on the use of machine learning models for predicting postoperative complications after major abdominal surgery.

Short-term outcome for high-risk patients after esophagectomy.

Transthoracic esophagectomy (TTE) for esophageal cancer facilitates mediastinal dissection; however, it has a significant impact on cardiopulmonary status. High-risk patients may therefore be better candidates for transhiatal esophagectomy (THE) in order to prevent serious complications. This study addressed short-term outcome following TTE and THE in patients that are considered to have a higher risk of surgery-related morbidity. This population-based study included patients who underwent a curative esophagectomy between 2011 and 2018, registered in the Dutch Upper GI Cancer Audit. The Charlson comorbidity index was used to assign patients to a low-risk (score ≤ 1) and high-risk group (score ≥ 2). Propensity score matching was applied to produce comparable groups between high-risk patients receiving TTE and THE. Primary endpoint was mortality (in-hospital/30-day mortality), secondary endpoints included morbidity and oncological outcomes. Additionally, a matched subgroup analysis was performed, including only cervical reconstructions. Of 5,438 patients, 945 and 431 high-risk patients underwent TTE and THE, respectively. After propensity score matching, mortality (6.3 vs 3.3%, P = 0.050), overall morbidity, Clavien-Dindo ≥ 3 complications, pulmonary complications, cardiac complications and re-interventions were significantly more observed after TTE compared to THE. A significantly higher mortality after TTE with a cervical reconstruction was found compared to THE (7.0 vs. 2.2%, P = 0.020). Patients with a high Charlson comorbidity index predispose for a complicated postoperative course after esophagectomy, this was more outspoken after TTE compared to THE. In daily practice, these outcomes should be balanced with the lower lymph node yield, but comparable positive node count and radicality after THE.

The prediction of surgical complications using artificial intelligence in patients undergoing major abdominal surgery: A systematic review.

BACKGROUND: Conventional statistics are based on a simple cause-and-effect principle. Postoperative complications, however, have a multifactorial and interrelated etiology. The application of artificial intelligence might be more accurate to predict postoperative outcomes. The objective of this study was to determine the current quality of studies describing the use of artificial intelligence in predicting complications in patients undergoing major abdominal surgery. METHODS: A literature search was performed in PubMed, Embase, and Web of Science. Inclusion criteria were (1) empirical studies including patients undergoing (2) any type of gastrointestinal surgery, including hepatopancreaticobiliary surgery, whose (3) complications or mortality were predicted with the use of (4) any artificial intelligence system. Studies were screened for description of method of validation and testing in methodology. Outcome measurements were sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve. RESULTS: From a total of 1,537 identified articles, 15 were included for the review. Among a large variety of algorithms used by the included studies, sensitivity was between 0.06 and 0.96, specificity was between 0.61 and 0.98, accuracy was between 0.78 and 0.95, and area under the receiver operating characteristic curve varied between 0.50 and 0.96. CONCLUSION: Artificial intelligence algorithms have the ability to accurately predict postoperative complications. Nevertheless, algorithms should be properly tested and validated, both internally and externally. Furthermore, a complete database and the absence of unsampled imbalanced data are absolute prerequisites for algorithms to predict accurately.

The Predictive Value of the Load Sharing Classification Concerning Sagittal Collapse and Posterior Instrumentation Failure: A Systematic Literature Review.

STUDY DESIGN: Systematic review. OBJECTIVE: In 1994, the Load Sharing Classification (LSC) was introduced to aid the choice of surgical treatment of thoracolumbar spine fractures. Since that time this classification system has been commonly used in the field of spine surgery. However, current literature varies regarding its use and predictive value in relation to implant failure and sagittal collapse. The objective of this study is to assess the predictive value of the LSC concerning the need for anterior stabilization to prevent sagittal collapse and posterior instrumentation failure. METHODS: An electronic search of PubMed, Medline, Embase, and the Cochrane Library was performed. Inclusion criteria were (1) cohort or clinical trial (2) including patients with thoracolumbar burst fractures (3) whose severity of the fractured vertebrae was assessed by the LSC. RESULTS: Five thousand eighty-two articles have been identified, of which 21 articles were included for this review. Twelve studies reported no correlation between the LSC and sagittal collapse or instrumentation failure in patients treated with short-segment posterior instrumentation (SSPI). Seven articles found no significant relation; 5 articles found no instrumentation failure at all. The remaining 9 articles experienced failure in patients with a high LSC or recommended a different surgical technique. CONCLUSIONS: Although the LSC was originally developed to predict the need for anterior stabilization in addition to SSPI, many studies show that SSPI only can be sufficient in treating thoracolumbar fractures regardless of the LSC. The LSC might have lost its value in predicting sagittal collapse and posterior instrumentation failure.

Implementation of robot-assisted Ivor Lewis procedure: Robotic hand-sewn, linear or circular technique?

BACKGROUND: Robot-assisted surgery for esophageal cancer is increasingly applied. Despite this upsurge, the preferential technique to create a robot-assisted intrathoracic anastomosis has not been established. DATA SOURCES: Bibliographic databases were searched to identify studies that performed a robot-assisted Ivor Lewis esophagectomy and described the technical details of the anastomotic technique. Out of 1701 articles, 16 studies were included for systematic review. CONCLUSIONS: This review shows that all technique used to create a thoracoscopic anastomosis can be adopted to robotic surgery. Techniques can be divided into three categories: robotic hand-sewn, circular stapling or linear stapling and robotic hand-sewn closure of the stapler defect. With limited robotic experience, circular stapling might be the preferred technique, however requires a well-trained bedside assistant. The linear stapling technique or hand-sewn technique are more challenging but enable experienced robotic surgeons to perform a controlled anastomosis without bedside support.

Dynamics of fertility impairment in childhood brain tumour survivors.

PURPOSE: Fertility impairment and recovery after chemo- and radiotherapy have been reported in both male and female childhood cancer survivors, but little is known about the dynamics. Our aim, therefore, was to describe the development of fertility impairment and possible recovery in childhood brain tumour survivors. METHODS: In this longitudinal study, we included 144 survivors, who were treated in two German paediatric oncology centres between 2000 and 2005. Fertility parameters were retrieved from medical records up to 12 years after diagnosis. RESULTS: Participants with age ≥13 years and formerly cranial irradiation ≥30 Gray (n = 23), including 83 % (n = 19) with craniospinal irradiation ≥30 Gray, had a higher median FSH concentration compared to 29 patients without chemoradiotherapy: 8.3 IU/l (IQR 6.5-11.2) versus 4.1 IU/l (IQR 3.2-5.1) 2 years after initial treatment; 8.9 IU/l (IQR 8.5-10.8) versus 4.2 IU/l (IQR 2.4-6.7) after 8 years; and 7.1 IU/l (IQR 6.7-7.7) versus 3.5 IU/l (IQR 2.8-4.2) after 10 years. Altogether, 11/65 women reported the occurrence of amenorrhoea 6.0 years (range 1-10) after diagnosis. Five of these women later developed a regular menstrual cycle without hormone replacement therapy. Patients' chance of recovery from fertility impairment was increased with time since diagnosis (p = 0.074). CONCLUSION: Signs of fertility impairment such as amenorrhoea and elevated FSH levels were observed at variable time points between 1 and 12 years after chemoradiotherapy. Decreasing FSH levels were observed 1-7 years after elevation and were interpreted either as an atrophy of the pituitary gland or as recovery from fertility impairment.

The muscle fiber type-fiber size paradox: hypertrophy or oxidative metabolism?

An inverse relationship exists between striated muscle fiber size and its oxidative capacity. This relationship implies that muscle fibers, which are triggered to simultaneously increase their mass/strength (hypertrophy) and fatigue resistance (oxidative capacity), increase these properties (strength or fatigue resistance) to a lesser extent compared to fibers increasing either of these alone. Muscle fiber size and oxidative capacity are determined by the balance between myofibrillar protein synthesis, mitochondrial biosynthesis and degradation. New experimental data and an inventory of critical stimuli and state of activation of the signaling pathways involved in regulating contractile and metabolic protein turnover reveal: (1) higher capacity for protein synthesis in high compared to low oxidative fibers; (2) competition between signaling pathways for synthesis of myofibrillar proteins and proteins associated with oxidative metabolism; i.e., increased mitochondrial biogenesis via AMP-activated protein kinase attenuates the rate of protein synthesis; (3) relatively higher expression levels of E3-ligases and proteasome-mediated protein degradation in high oxidative fibers. These observations could explain the fiber type-fiber size paradox that despite the high capacity for protein synthesis in high oxidative fibers, these fibers remain relatively small. However, it remains challenging to understand the mechanisms by which contractile activity, mechanical loading, cellular energy status and cellular oxygen tension affect regulation of fiber size. Therefore, one needs to know the relative contribution of the signaling pathways to protein turnover in high and low oxidative fibers. The outcome and ideas presented are relevant to optimizing treatment and training in the fields of sports, cardiology, oncology, pulmonology and rehabilitation medicine.

A validation analysis of two self-reported HAM-D6 versions.

OBJECTIVE: The six items of the clinician-administrated Hamilton Depression Scale (HAM-D(6)) cover the core items of depressive states reflecting the antidepressive effect of medication. In this study, the two self-reported versions of the HAM-D(6) have been psychometrically validated to ensure the unidimensionality of this administration form in patients with mild-to-moderate depression. METHOD: The item response theory analysis of Mokken was used to test the unidimensionality of both the Interactive Voice Recording System (IVRS) version of the HAM-D(6) and a paper-and-pencil self-reported version (S-HAM-D(6)). Patients with typical major depression and with seasonal affective disorder were included. RESULTS: The Mokken analysis showed that the two self-reported versions of the HAM-D(6) obtained coefficients of homogeneity above 0.40, similar to the clinician-rated HAM-D(6) and thus implying unidimensionality. By contrast, the full HAM-D(17) versions (self-reported as well as clinician-rated) obtained coefficients of homogeneity below 0.40, implying that the HAM-D(17) is a multidimensional scale. CONCLUSION: The analysis show that both the IVRS version and the S-HAM-D(6) version are unidimensional self-rating scales for the measurement of depressive states.

Postnatal development of fiber type composition in rabbit jaw and leg muscles.

We examined the difference in fiber type composition and cross-sectional areas during postnatal development in male rabbit jaw muscles and compared these with changes in leg muscles. The myosin heavy chain (MyHC) content of the fibers was determined by immunohistochemistry. No fiber type difference was found between the jaw muscles in 20-week-old rabbits. However, the way this adult fiber type composition was reached differed between the muscles. The deep temporalis, medial pterygoid, and superficial masseter displayed an increase in alpha fibers during early and a decrease during late postnatal development. Other jaw muscles displayed an increase in alpha fibers during early development only. In contrast, alpha fibers were not found in the soleus, in which fiber type changes were completed at week 4. The gastrocnemius muscle did not change its fiber type composition. Initially, fibers in jaw-opening muscles had larger cross-sectional areas than in other muscles, but they increased less during development. Although there were no large differences in the fiber type composition of muscles in young adult rabbits, large differences were found in the jaw muscles, but not in the leg muscles, during development. In part, these developmental changes in fiber percentages within the jaw muscles can be explained by functional modifications in this muscle group. In the present study, the deep temporalis, medial pterygoid, and superficial masseter showed the most dramatic percent changes in fibers during postnatal development.

Is fiber-type composition related to daily jaw muscle activity during postnatal development?

AIM: Muscles containing large numbers of slow-contracting fibers are generally more active than muscles largely composed of fast fibers. This relationship between muscle activity and phenotype suggests that (1) changes in fiber-type composition during postnatal development are accompanied by changes in daily activity and (2) individual variations in fiber-type composition are related to similar variations in daily muscle activity. METHODS: The masseter and digastric muscles of 23 New Zealand White rabbits (young, juvenile and adult) were examined for their phenotype (myosin heavy chain content) and their daily activity (total daily number of activity bursts). RESULTS: During development, the masseter showed a strong increase in the number of fast-type fibers compared to the number of slow-type fibers. During development, also the number of powerful bursts in the masseter increased. The digastric showed no significant changes in fiber types or burst numbers. Within each muscle, across individual animals, no significant correlations (R < 0.70) were found between any of the fiber types and daily burst numbers in any of the age groups. CONCLUSIONS: The results suggest that activity-related influences are of relatively minor importance during development and that other factors are dominant in determining fiber-type composition.

Postnatal transitions in myosin heavy chain isoforms of the rabbit superficial masseter and digastric muscle.

We investigated the early (< 8 weeks) and late (> 8 weeks) postnatal development of the fibre type composition and fibre cross-sectional area in the superficial masseter and digastric muscle of male rabbits. It was hypothesized, first, that due to the transition between suckling and chewing, during early postnatal development the increase in the proportion of slow fibre types and in fibre cross-sectional areas would be larger in the masseter than in the digastric; and second, that due to the supposed influence of testosterone during late postnatal development, the proportion of slow fibre types in both muscles would decrease. Fibre types were classified by immunostaining according to their myosin heavy chain (MyHC) content. The proportion of slow fibre types significantly increased in the masseter, from 7% at week 1 to 47% at week 8, and then decreased to 21% at week 20, while in the digastric it increased from 5% in week 1 to 19% at week 8 and remained the same thereafter. The changes in the proportion of fast fibre types were the opposite. The remarkable increase and decrease in the proportion of slow fibre types in the masseter was attributed predominantly to MyHC-cardiac alpha fibres. During early development, the cross-sectional area of all fibres in both muscles increased. However, only the fast fibre types in the masseter continued to grow further after week 8. Before weaning, the fast fibre types in the digastric were larger than those in the masseter, but after week 8, they became larger in the masseter than in the digastric. In adult animals, masseter and digastric had the same percentage of fast fibre types, but these fibres were almost twice as large in masseter as in digastric.

Daily activity of the rabbit jaw muscles during early postnatal development.

Early postnatal development of the jaw muscles is characterized by the transition from suckling to chewing behavior. As chewing develops the jaw closing muscles become more powerful compared with the jaw openers. These changes are likely to affect the amount of daily muscle activity. Therefore, the purpose of this study was to characterize for a jaw opener (digastric) and jaw closer (masseter) the total duration of daily muscle activity (i.e. the duty time), and the daily burst numbers and lengths during early postnatal development. Using radiotelemetry the activity of these muscles was recorded in 10 young New Zealand White rabbits between three and eight weeks of age. Fiber-type composition was analyzed at eight weeks of age by determining the myosin heavy chain content of the fibers. During postnatal development both muscles showed no significant decrease or increase in their daily activity. However, the interindividual variation of the duty time and burst number significantly decreased. There were no significant differences between the digastric and masseter except for the most powerful activities at eight weeks of age, where the masseter showed a significantly higher duty time and burst number than the digastric. The masseter contained a higher number of slow-type fibers expressing myosin heavy chain-I and myosin heavy chain-cardiac alpha than the digastric. The present results suggest that the amount of jaw muscle activation is already established early during postnatal development, before the transition from suckling to chewing behavior. This amount of activation seems to be related to the number of slow-type fibers.

Fibre-type composition of rabbit jaw muscles is related to their daily activity.

Skeletal muscles contain a mixture of fibres with different contractile properties, such as maximum force, contraction velocity and fatigability. Muscles adapt to altered functional demands, for example, by changing their fibre-type composition. This fibre-type composition can be changed by the frequency, duration and presumably the intensity of activation. The aim of this study was to analyse the relationship between the spontaneous daily muscle activation and fibre-type composition in rabbit jaw muscles. Using radio-telemetry combined with electromyography, the daily activity of five jaw muscles was characterized in terms of the total duration of muscle activity (duty time) and the number of activity bursts. Fibre-type composition of the muscles was classified by analysing the myosin heavy chain content of the fibres. The amount of slow-type fibres was positively correlated to the duty time and the number of bursts only for activations exceeding 20-30% of the maximum activity per day. Furthermore, cross-sectional areas of the slow-type fibres were positively correlated to the duty time for activations exceeding 30% of the maximum activity. The present data indicate that the amount of activation above a threshold (> 30% peak activity) is important for determining the fibre-type composition and cross-sectional area of slow-type fibres of a muscle. Activation above this threshold occurred only around 2% of the time in the jaw muscles, suggesting that contractile properties of muscle fibres are maintained by a relatively small number of powerful contractions per day.

Burst characteristics of daily jaw muscle activity in juvenile rabbits.

Muscle activation varies with different behaviors and can be quantified by the level and duration of activity bursts. Jaw muscles undergo large anatomical changes during maturation, which are presumably associated with changes in daily muscle function. Our aim was to examine the daily burst number, burst length distribution and duty time (fraction of the day during which a muscle was active) of the jaw muscles of juvenile male rabbits (Oryctolagus cuniculus). A radio-telemetric device was implanted to record muscle activity continuously from the digastric, superficial and deep masseter, medial pterygoid and temporalis during maturation week 9-14. Daily burst characteristics and duty times were determined for activations, including both powerful and non-powerful motor behavior. All muscles showed constant burst numbers, mean burst lengths and duty times during the recording period. Including all behavior, the temporalis showed significantly larger daily burst numbers (205,000) and duty times (18.2%) than the superficial and deep masseter (90,000; 7.5%). Burst numbers and duty times were similar for the digastric (120,000; 11.1%) and medial pterygoid (115,000; 10.4%). The temporalis and deep masseter showed many short low activity bursts (0.05 s), the digastric showed many long bursts (0.09 s). For activations during powerful behaviors the superficial masseter and medial pterygoid had the largest burst numbers and duty times. Both muscles showed similar burst characteristics for all activation levels. It was concluded that activation of the jaw muscles is differently controlled during powerful and non-powerful motor behaviors and the functional organization of motor control patterns does not vary from 9 to 14 weeks of age.

Long-term registration of daily jaw muscle activity in juvenile rabbits.

Understanding control of muscles during various tasks and their adaptive changes requires information on all motor behavior used throughout the day. The total duration of muscle activity depends on the magnitude of its activation and can change during maturation. Therefore, the purpose of this study was to examine the duration of muscle activity (i.e. duty time) exceeding various activity levels in maturing jaw muscles. A telemetric device was implanted into nine juvenile male New Zealand White rabbits to continuously record muscle activity during maturation weeks 9-14. Electrodes were inserted into digastric, superficial and deep masseter, medial pterygoid, and temporalis muscles. Duty times (expressed as a percentage of time) were calculated for activation exceeding different levels (5-90%) of EMG peak activity per 24-h period. At 10 weeks of age, for activation exceeding the 5% level, the duty time of the temporalis (20.0+/-5.2%) was statistically significantly higher than that of the medial pterygoid (11.2+/-1.5%), digastric (11.0+/-5.1%), superficial (12.6+/-5.6%), and deep masseter (8.6+/-5.5%). Duty times declined with increasing activity level. For activation exceeding the 40% level the duty times of the superficial masseter and medial pterygoid were significantly higher than those of the other muscles. During maturation none of the muscles showed a significant change in duty time. However, for activation exceeding the 5% level, the inter-individual variation in duty time decreased significantly for the digastric, and superficial and deep masseter.

Variation in daily masticatory muscle activity in the rabbit.

The daily use of masticatory muscles remains largely unclear, since continuous recordings were limited in space and time. This study's purpose was to use radio-telemetry to examine daily muscle use and its inter- and intra-individual variations. A telemetric device was implanted into the rabbit masseter, and the transmitted signals were digitally stored for 7 days. Muscle use was analyzed by calculation of the total time each muscle was activated above 5, 20, and 50% of the day's peak activity. Rabbits (n = 6) spent only 2% of the time chewing. Muscles were activated up to 20% of the total time at levels exceeding 5% of peak activity, and only about 0.5% of the time in forceful behaviors utilizing 50% of maximum contraction. It can be concluded that daily muscle use remained constant during succeeding days, but differed significantly among muscle regions and individuals.

[Do local nursing home inmates get appropriate medication?--comments on the quality of drug application in nursing homes]. / Erhalten die Bewohner von Pflegeheimen vor Ort die richtigen Arzneimittel?--Zur Qualität beim Stellen von Arzneimitteln in Pflegeheimen.

BACKGROUND: Preparing prescribed drugs in unit dose systems for often multimorbid patients in nursing homes is a responsible and difficult task for the nursing personnel. The aim of this study was to increase the knowledge on the quality level of drug supply. METHOD: In a non-representative sample the local inspectorates for pharmacies in North Rhine-Westphalia compared the actually available drugs with the prescribed drugs documented in nursing homes. Participation was voluntary. RESULTS: In 50 % of the investigated nursing homes no medication error could be found. 30 percent of the observed cases showed only one error. In 20 percent the individual preparation of drugs in unit dose systems should be improved. Nursing homes with specific quality standards showed the least number of errors. Oral and not documented arrangements seem to be a common cause for avoidable errors.