Machine learning in data abstraction: A computable phenotype for sepsis and septic shock diagnosis in the intensive care unit

BACKGROUND

With the recent change in the definition (Sepsis-3 Definition) of sepsis and septic shock, an electronic search algorithm was required to identify the cases for data automation. This supervised machine learning method would help screen a large amount of electronic medical records (EMR) for efficient research purposes.

AIM

To develop and validate a computable phenotype via supervised machine learning method for retrospectively identifying sepsis and septic shock in critical care patients.

METHODS

A supervised machine learning method was developed based on culture orders, Sequential Organ Failure Assessment (SOFA) scores, serum lactate levels and vasopressor use in the intensive care units (ICUs). The computable phenotype was derived from a retrospective analysis of a random cohort of 100 patients admitted to the medical ICU. This was then validated in an independent cohort of 100 patients. We compared the results from computable phenotype to a gold standard by manual review of EMR by 2 blinded reviewers. Disagreement was resolved by a critical care clinician. A SOFA score ≥ 2 during the ICU stay with a culture 72 h before or after the time of admission was identified. Sepsis versions as V1 was defined as blood cultures with SOFA ≥ 2 and Sepsis V2 was defined as any culture with SOFA score ≥ 2. A serum lactate level ≥ 2 mmol/L from 24 h before admission till their stay in the ICU and vasopressor use with Sepsis-1 and-2 were identified as Septic Shock-V1 and-V2 respectively.

RESULTS

In the derivation subset of 100 random patients, the final machine learning strategy achieved a sensitivity-specificity of 100% and 84% for Sepsis-1, 100% and 95% for Sepsis-2, 78% and 80% for Septic Shock-1, and 80% and 90% for Septic Shock-2. An overall percent of agreement between two blinded reviewers had a k = 0.86 and 0.90 for Sepsis 2 and Septic shock 2 respectively. In validation of the algorithm through a separate 100 random patient subset, the reported sensitivity and specificity for all 4 diagnoses were 100%-100% each.

CONCLUSION

Supervised machine learning for identification of sepsis and septic shock is reliable and an efficient alternative to manual chart review.

Gemcitabine plus capecitabine (Gem-Cape) biweekly in chemorefractory metastatic colorectal cancer

Purpose

A proportion of patients with metastatic colorectal cancer (mCRC) are still able to continue with active therapy after their progression to fluoropyrimidines, oxaliplatin, and irinotecan regimens. Studies suggest that gemcitabine and fluoropyrimidines are synergic antimetabolites. The purpose was to evaluate gemcitabine–capecitabine (Gem–Cape) in heavily pretreated mCRC and to thus assess possible predictive factors for progression-free survival (PFS) and overall survival (OS).

Patients and methods

This analysis was performed on 119 evaluable patients pretreated with fluoropyrimidines, oxaliplatin, irinotecan, and biological agents between June 2001 and July 2011. Patients received gemcitabine 1,000 mg/m² day 1 and capecitabine 1,000 mg/m²bid for 7 days every 2 weeks.

Results

The general characteristics were ECOG 0–1, 89 %; male, 68 %, and median age 63 years. In total, 61 % had received two chemotherapy lines, while 39 % had received three or more. Objective response rates and stable disease rates at 3 months were 6.72 and 37.81 %, equalling a clinical benefit of 44.53 %. The median PFS and OS were 2.87 months [95 % confidence interval (CI) 2.53–3.17 months] and 6.53 months (95 % CI 5.33–8.77), respectively. The most frequent toxicities were grades 1–2, anemia (22 %), thrombocytopenia (10 %), and hand–foot syndrome (9 %); grade ≥3, diarrhea (2 %), with no treatment-related discontinuations. No treatment-related deaths were reported. Statistical significance was obtained by subgroups, assessing clinical benefits and objective responses for PFS and OS. Moreover, patients under 65 tended to have a better PFS.

Conclusion

These data suggest that Gem–Cape is a tolerable and feasible regimen, associated with clinical benefit in non-selected, heavily pretreated, mCRC patients.

Protective role of testosterone in ischemia-reperfusion-induced acute kidney injury

Men are at greater risk for renal injury and dysfunction after acute ischemia-reperfusion (I/R) than are women. Studies in animals suggest that the reason for the sex difference in renal injury and dysfunction after I/R is the protective effect of estrogens in females. However, a reduction in testosterone in men is thought to play an important role in mediating cardiovascular and renal disease, in general. In the present study, we tested the hypothesis that I/R of the kidney reduces serum testosterone, and that contributes to renal dysfunction and injury. Male rats that were subjected to renal ischemia of 40 min followed by reperfusion had a 90% reduction in serum testosterone by 3 h after reperfusion that remained at 24 h. Acute infusion of testosterone 3 h after reperfusion attenuated the increase in plasma creatinine and urinary kidney injury molecule-1 (KIM-1) at 24 h, prevented the reduction in outer medullary blood flow, and attenuated the increase in intrarenal TNF-α and the decrease in intrarenal VEGF at 48 h. Castration of males caused greater increases in plasma creatinine and KIM-1 at 24 h than in intact males with renal I/R, and treatment with anastrozole, an aromatase inhibitor, plus testosterone almost normalized plasma creatinine and KIM-1 in rats with renal I/R. These data show that renal I/R is associated with sustained reductions in testosterone, that testosterone repletion protects the kidney, whereas castration promotes renal dysfunction and injury, and that the testosterone-mediated protection is not conferred by conversion to estradiol.

Testosterone supplementation in male obese Zucker rats reduces body weight and improves insulin sensitivity but increases blood pressure

Androgen levels are lower in obese men as compared with normal weight individuals. However, there are no safety data regarding the chronic use of androgen supplements in middle-aged men. The present study was undertaken to determine the cardiovascular and metabolic effects of chronic (10 weeks) testosterone treatment in male obese Zucker rats, starting at 22 weeks of age, when testosterone levels were significantly decreased. Testosterone supplements increased plasma levels, 10-fold in both obese Zucker rats and lean Zucker rats. In obese Zucker rats, testosterone supplements reduced body weight, plasma insulin, and cholesterol levels and improved the oral glucose tolerance test. None of these parameters were affected in lean Zucker rats. Mean arterial pressure was significantly increased in obese Zucker rats but not lean Zucker rats. Testosterone supplements increased proteinuria and accelerated renal injury in lean Zucker rats only. Thus, treatment of obese men with chronic testosterone supplements should be done with careful monitoring of blood pressure.

Osteonecrosis in retrieved femoral heads after failed resurfacing arthroplasty of the hip

We present the histological findings of bone retrieved from beneath the femoral components of failed metal-on-metal hip resurfacing arthroplasties. Of a total of 377 patients who underwent resurfacing arthroplasty, 13 required revision; for fracture of the femoral neck in eight, loosening of a component in three and for other reasons in two. None of these cases had shown histological evidence of osteonecrosis in the femoral bone at the time of the initial implantation. Bone from the remnant of the femoral head showed changes of osteonecrosis in all but one case at revision. In two cases of fracture which occurred within a week of implantation, the changes were compatible with early necrosis of the edge of the fracture. In the remaining six fractures, there were changes of established osteonecrosis. In all but one of the non-fracture cases, patchy osteonecrosis was seen. We conclude that histological evidence of osteonecrosis is a common finding in failed resurfaced hips. Given that osteonecrosis is extensive in resurfaced femoral heads which fail by fracture, it is likely to play a role in the causation of these fractures.

Arthroscopic ACL reconstruction: a 5-9 year follow-up

Arthroscopic ACL reconstruction has a satisfactory functional outcome of up to 90%, but there are few long-term prospective studies. This prospective study presents the outcomes of ACL reconstruction in terms of laxity, function and degenerative change, after a mean follow-up of 7 years. Function was assessed using the Lysholm and Tegner Activity Scores, laxity using the Stryker Knee Laxity Tester, employing maximum manual effort, and degenerative change was assessed as joint line narrowing on standardised radiographs. At latest follow-up, the mean Lysholm score improved from 70 to 87 and the Tegner from 4 to 7 (P<0.001). AP translation also improved (P<0.001). The incidence of early degenerative change was 50% and although this appeared to be associated with a previous meniscectomy, the correlation was not significant (P=0.06). In conclusion, the improved functional scores and laxity are sustained beyond 7 years but the 50% incidence of early degenerative change may be a cause for concern.

Clinical screening for developmental dysplasia of the hip in Northern Ireland

PROBLEM

The incidence of late diagnosed developmental dysplasia of the hip requiring surgery in Northern Ireland is high. The reported incidence was 1.14 per 1000 children born during 1983-7.

DESIGN

Comparative retrospective study.

BACKGROUND AND SETTING

Clinical screening programme in Northern Ireland. Key measure for improvement: Reduced rate of operative intervention in children with developmental dysplasia of the hip detected after 6 months of age.

STRATEGIES FOR CHANGE

Increased emphasis on staff training, introduction of a centralised nurse led clinic to improve access to orthopaedic surgeons, and increased use of ultrasonography.

EFFECTS OF CHANGE

The incidence of developmental dysplasia of the hip diagnosed after 6 months in children born between January 1991 and December 1997 fell to 0.59 per 1000, presumably due to improved early detection. Nevertheless, 29 (16%) of the affected hips were not diagnosed when the child was first referred in the first 3 months of life. In addition, for 27 affected hips in children diagnosed after the age of 6 months there was a known risk factor (family history or breech delivery).

LESSONS LEARNT

Improvements to screening processes can reduce late incidence of developmental dysplasia of the hip. Further steps to improve detection in children with known risk factors and rate of detection at first referral could reduce late presentation further.

Late outcome of isolated tibial fractures treated by intramedullary nailing: the correlation between disease-specific and generic outcome measures

OBJECTIVES

To measure the late morbidity of nailed isolated tibial fractures, using both a generic health score and disease-specific scores. To determine the correlation between the two types of outcome measure.

DESIGN

Retrospective study, using a combination of case notes and radiographic review plus current clinical assessment.

SETTING

Fracture Outcomes Research Unit in a U.K. teaching hospital.

PATIENTS

Eighty-three patients with isolated fractures of the tibial diaphysis. Follow-up time was a minimum of three years from injury (mean fifty-seven months).

INTERVENTION

All patients were treated primarily by closed, reamed intramedullary nailing.

OUTCOME MEASUREMENTS

Iowa Knee and Ankle Scores, visual analogue pain scores for fracture site and knee and ankle joints, and the Short Form 36 health status questionnaire.

RESULTS

Sixty-four (77.1%) fractures united after the first procedure. Twenty-nine (34.9%) patients had pain around the knee at rest, fifty-nine (71.1%) had difficulty in kneeling, and thirteen (15.7%) were still experiencing some pain at their fracture site; 69% of patients had excellent results based on the Iowa scores as well as the SF-36 scores. Pain at the knee correlated with low Physical Component Summary and Mental Component Summary scores, and fracture site pain correlated with only low Physical Component Summary score. There was a significant correlation between the disease-specific scores and the SF-36 scores, and only patients with an excellent Iowa grade had "normal" SF-36 scores.

CONCLUSION

After tibial nailing, mild deficits registered by Iowa scores are associated with a significant disability and unhappiness as registered by the SF-36. According to the patient-oriented outcomes tool, 31% of late results are "unsatisfactory."

Total knee arthroplasty without patellar resurfacing in isolated patellofemoral osteoarthritis

Thirty-one patients (33 knees) with symptomatic patellofemoral osteoarthritis and minimal tibiofemoral changes underwent LCS total knee arthroplasty without patellar resurfacing. Average age was 73 years (range, 58-89 years) with a female-to-male ratio of 5:1. Average follow-up was 20 months (range, 12-40 months). All except 4 patients had grade 3 or 4 patellofemoral osteoarthritis. Preoperatively, all patients had significant knee pain. Sleep disturbance was reported in 21 patients. All but 10 patients required walking aids. Average range of motion was 108 degrees (range, 80-125 degrees ). At latest review, 21 knees were pain-free, the remaining 12 knees being described as having only occasional knee pain. Two patients continued to have night pain. Average range of motion was 104 degrees (range, 70-135 degrees ). Lateral patellar tilt improved in all but 5 knees by an average of 7 degrees (range, 1-26 degrees ). Patellar congruency improved in all but 3 knees by an average of 18% (range, 3-63%). None of the patients to date have required revision surgery. Total knee arthroplasty without patellar resurfacing is an effective option in older patients with isolated patellofemoral osteoarthritis.

Percutaneous pin fixation of intercondylar fractures in young children

T-condylar fractures of the distal humerus are very rare in children. When they do occur they tend to affect those approaching skeletal maturity. Most agree that the undisplaced fracture can be managed conservatively. With increasing displacement and comminution the opinions tend to differ. As an alternative to open reduction and internal fixation we report the use of closed reduction and percutaneous pin fixation for displaced and comminuted T-condylar fractures in a series of three young children. In addition to the classical medial and lateral column fixation we report the use of a transcondylar wire to stabilise the distal fragments and discuss the use of intra-operative arthrography in low supracondylar fractures to exclude a missed intercondylar extension on plain xrays. Although small this series represents the largest series of children less than eight years of age.

Dia-metaphyseal distal tibial fractures--treatment with a shortened intramedullary nail: a review of 15 cases

Fifteen patients were reviewed retrospectively with distal tibial fractures treated with a reamed intramedullary nail which had approximately 1 cm removed just distal to the lowermost locking screw. There were 15 patients (nine males and six females). All patients had returned to normal activities of daily living. Eleven patients could perform all leisure activities with no symptoms and three had only minor discomfort, which did not preclude sport. All fractures united, 12 uneventfully and three after a secondary surgical procedure. Three patients had malalignment defined as varus-valgus angulation or recurvatum of 5 degrees or greater. Whilst technically challenging, intramedullary nailing for dia-metaphyseal distal tibial fractures represents a safe and reliable method for managing these injuries. This represents the first report in the English Language literature specifically examining treatment with a shortened tibial nail.

Periprosthetic femoral fractures in Northern Ireland

Twenty-five patients with periprosthetic femoral fractures were admitted to the Ulster Hospital between August 1998 and May 2000. Average age was 77 years (range, 42-96 years) with a female to male ratio of 2:1. Twenty-four of the fractures occurred following primary joint arthroplasty on average 7.6 years from insertion of the primary prosthesis. One patient sustained an intraoperative fracture during revision surgery. In the majority (80%), the periprosthetic femoral fracture was associated with a traumatic event. On average, two days elapsed from the time of injury until admission to our unit. Time from admission to surgery was on average 4 days. All patients were treated by open fracture fixation. Duration of stay in the fracture unit was on average 20 days. Prior to their fracture 92% of patients were living at home and 84% were mobile either unaided or with the use of a stick. At most recent review, 72% are back living at home and 60% are mobile either unaided or with the use of a stick. We emphasise that there is the likelihood of an increase in periprosthetic femoral fractures due to the increasing number of primary arthroplasties being performed on a more active, ageing population. Preventative measures and cost implications are also discussed.

Implant failure in tibial nailing

Between 1991 and 1995 five hundred and twenty tibial diaphyseal fractures were treated with intramedullary nailing in Northern Ireland. We retrospectively reviewed three hundred and thirty eight patients in three out of the four fracture units in Northern Ireland. Within this group there were three hundred and forty fractures and we identified twenty five episodes of implant failure. This group of patients had a higher percentage of open injuries with a higher degree of comminution and had been treated with smaller diameter nails when compared with the group of patients, who had no implant failure. Failure occurred most frequently at the transverse proximal locking screw when a single screw was used. Fractures in the distal third of the tibia had a higher incidence of nail breakage. We would recommend early elective dynamisation and the use of statically locked larger diameter nails, especially in comminuted or distal third fractures.

Osteoid osteoma of the scapular neck: a case report

Osteoid osteoma localised in the scapula are very rare. We report the case of an 11-year-old girl, who presented with an osteoid osteoma at the neck of the glenoid. This was excised en bloc after being located accurately by computed tomography. This case report demonstrates the difficulty in the approach to the excision of this unusually located lesion.