Comparative performance of intensive care mortality prediction models based on manually curated versus automatically extracted electronic health record data

INTRODUCTION

Benchmarking intensive care units for audit and feedback is frequently based on comparing actual mortality versus predicted mortality. Traditionally, mortality prediction models rely on a limited number of input variables and significant manual data entry and curation. Using automatically extracted electronic health record data may be a promising alternative. However, adequate data on comparative performance between these approaches is currently lacking.

METHODS

The AmsterdamUMCdb intensive care database was used to construct a baseline APACHE IV in-hospital mortality model based on data typically available through manual data curation. Subsequently, new in-hospital mortality models were systematically developed and evaluated. New models differed with respect to the extent of automatic variable extraction, classification method, recalibration usage and the size of collection window.

RESULTS

A total of 13 models were developed based on data from 5,077 admissions divided into a train (80%) and test (20%) cohort. Adding variables or extending collection windows only marginally improved discrimination and calibration. An XGBoost model using only automatically extracted variables, and therefore no acute or chronic diagnoses, was the best performing automated model with an AUC of 0.89 and a Brier score of 0.10.

DISCUSSION

Performance of intensive care mortality prediction models based on manually curated versus automatically extracted electronic health record data is similar. Importantly, our results suggest that variables typically requiring manual curation, such as diagnosis at admission and comorbidities, may not be necessary for accurate mortality prediction. These proof-of-concept results require replication using multi-centre data.

[Cardiogenic shock due to phosphine poisoning]

BACKGROUND

Toxic inhalations form a rare cause of poisoning in the Netherlands. The initial symptoms of toxic inhalations may appear similar to acute viral infections. In the maritime sector aluminum or zinc phosphide is used to overcome rodent infestations during transportation.

CASE DESCRIPTION

Here we discuss two patients intoxicated with gaseous phosphide used as fumigant in the transport of grains. The exposure to phosphide gas resulted in respiratory and gastrointestinal tract symptoms. Upon admission one of the patients deteriorated resulting in respiratory insufficiency, multi-organ failure and cardiogenic shock.

CONCLUSION

Phosphide gas poisoning forms a rare cause for transient acute heart and multiorgan failure largely due to mitochondria dysfunction. In the case of unexplained incapacitation of multiple patients and/or pets toxic inhalations should differentially diagnostically be considered.

Impact of reduced antibiotic treatment duration on antimicrobial resistance in critically ill patients in the randomized controlled SAPS-trial

Background

In the previously reported SAPS trial (https://clinicaltrials.gov/ct2/show/NCT01139489), procalcitonin-guidance safely reduced the duration of antibiotic treatment in critically ill patients. We assessed the impact of shorter antibiotic treatment on antimicrobial resistance development in SAPS patients.

Materials and methods

Cultures were assessed for the presence of multi-drug resistant (MDR) or highly resistant organisms (HRMO) and compared between PCT-guided and control patients. Baseline isolates from 30 days before to 5 days after randomization were compared with those from 5 to 30 days post-randomization. The primary endpoint was the incidence of new MDR/HRMO positive patients.

Results

In total, 8,113 cultures with 96,515 antibiotic test results were evaluated for 439 and 482 patients randomized to the PCT and control groups, respectively. Disease severity at admission was similar for both groups. Median (IQR) durations of the first course of antibiotics were 6 days (4-10) and 7 days (5-11), respectively (p = 0.0001). Antibiotic-free days were 7 days (IQR 0-14) and 6 days (0-13; p = 0.05). Of all isolates assessed, 13% were MDR/HRMO positive and at baseline 186 (20%) patients were MDR/HMRO-positive. The incidence of new MDR/HRMO was 39 (8.9%) and 45 (9.3%) in PCT and control patients, respectively (p = 0.82). The time courses for MDR/HRMO development were also similar for both groups (p = 0.33).

Conclusions

In the 921 randomized patients studied, the small but statistically significant reduction in antibiotic treatment in the PCT-group did not translate into a detectable change in antimicrobial resistance. Studies with larger differences in antibiotic treatment duration, larger study populations or populations with higher MDR/HRMO incidences might detect such differences.

An Experimental Computer Network for Mcdical Data Processing

Methods for supplying medical personnel, especially in isolated areas, with the same sophisticated medical information and computational facilities that are available in major medical centers, were investigated. Inexpensive, readily available input/output terminals, including the pushbutton telephone, were tested with several biomedical application programs. An experimental network, consisting of several independent commercial time-sharing computers linked to user terminals through a small communication control computer, was constructed to demonstrate an efficient and flexible approach to remote computer access. The communication control computer, acting as a message handling and translating interface, allowed the use of a uniform terminal control language and common data handling conventions. By linking to the most powerful commercial time-sharing systems available, a reliable medical data processing network was established without a major investment in computer hardware or system software. This experimental work is a major part of the Medical Information Telecommunication Project in the Division of Computer Research and Technology (DCRT) at the National Institutes of Health (NIH).

Cooling a mechanical resonator with nitrogen-vacancy centres using a room temperature excited state spin-strain interaction

Cooling a mechanical resonator mode to a sub-thermal state has been a long-standing challenge in physics. This pursuit has recently found traction in the field of optomechanics in which a mechanical mode is coupled to an optical cavity. An alternate method is to couple the resonator to a well-controlled two-level system. Here we propose a protocol to dissipatively cool a room temperature mechanical resonator using a nitrogen-vacancy centre ensemble. The spin ensemble is coupled to the resonator through its orbitally-averaged excited state, which has a spin–strain interaction that has not been previously studied. We experimentally demonstrate that the spin–strain coupling in the excited state is 13.5±0.5 times stronger than the ground state spin–strain coupling. We then theoretically show that this interaction, combined with a high-density spin ensemble, enables the cooling of a mechanical resonator from room temperature to a fraction of its thermal phonon occupancy.

An efficient cooling mechanism for nanoscale mechanical resonators would help improve their properties for use in sensing applications. Here, the authors demonstrate a strong interaction between NV centres and a resonator and show how it could be harnessed to achieve a large cooling rate.

A Young Man With Severe and Disabling Complications of Septic Shock

A young man had severe septic shock with multiorgan failure due to necrotizing fasciitis caused by group A streptococcus after endoscopic repair of a preperitoneal inguinal hernia. He was treated with surgical exploration and antibiotics and resuscitated with fluids, vasopressors, and inotropic agents. He survived this critical illness, but when he woke up from sedation, his vision was lost in both eyes. Ophthalmological evaluation revealed minimal peripapillary retinal hemorrhages without signs of papillary edema. Visually evoked potentials were negative. Magnetic resonance imaging did not show a cause of the visual damage. The patient had bilateral ischemic optic neuropathy diagnosed. Two weeks later, unilateral sudden deafness also developed. The acquired blindness and hearing loss were unchanged after more than 1 year and seem to be permanent, severely disabling this young survivor of septic shock.

Acute pontine infarction after percutaneous coronary intervention: a very rare but devastating complication

A 64-year-old man suffering from an acute posterior wall myocardial infarction underwent primary percutaneous coronary intervention. After several aspiration attempts, tirofiban infusion and pre- and post-dilatation, a bare-metal stent was successfully implanted in the culprit right coronary artery. While the patient did not show any neurological symptoms before or during the procedure, he exhibited hemiplegia and loss of spontaneous speech. Additional magnetic resonance imaging showed an extensive brain stem infarction. This is the first report of a brain stem infarction as a complication of percutaneous coronary intervention.

New frontiers for health information systems using Epi Info in developing countries: Structured application framework for Epi Info (SAFE)

BACKGROUND

For more than two decades, Epi Info software has been used to meet the data management, analysis, and mapping needs of public health professionals in more than 181 countries and 13 languages. Until now, most Epi Info systems have been relatively simple, mainly because of a lack of detailed and structured guidance for developing complex systems.

OBJECTIVE AND RESULTS

We created the structured application framework for Epi Info (SAFE), which is a set of guidelines that allows developers to create both simple and complex information systems using accepted good programming practices. This has resulted in application code blocks that are re-useable and easy to maintain, modify, and enhance. The flexibility of SAFE allows various aggregate and case-based application modules to be rapidly created, combined, and updated to create health information systems or sub-systems enabling continuous, incremental enhancement as national and local capacity increases.

CONCLUSIONS

SAFE and Epi Info are both cost-free and have low system requirements--characteristics that render this framework and software beneficial for developing countries.

Public-health impact of accelerated measles control in the WHO African Region 2000-03

BACKGROUND

In 2000, the WHO African Region adopted a plan to accelerate efforts to lower measles mortality with the goal of decreasing the number of measles deaths to near zero. By June, 2003, 19 African countries had completed measles supplemental immunisation activities (SIA) in children aged 9 months to 14 years as part of a comprehensive measles-control strategy. We assessed the public-health impact of these control measures by use of available surveillance data.

METHODS

We calculated percentage decline in reported measles cases during 1-2 years after SIA, compared with 6 years before SIA. On the basis of data from 13 of the 19 countries, we assumed that the percentage decline in measles deaths equalled that in measles cases. We also examined data on routine and SIA measles vaccine coverage, measles case-based surveillance, and suspected measles outbreaks.

FINDINGS

Between 2000 and June, 2003, 82.1 million children were targeted for vaccination during initial SIA in 12 countries and follow-up SIA in seven countries. The average decline in the number of reported measles cases was 91%. In 17 of the 19 countries, measles case-based surveillance confirmed that transmission of measles virus, and therefore measles deaths, had been reduced to low or very low rates. The total estimated number of deaths averted in the year 2003 was 90,043. Between 2000 and 2003 in the African Region as a whole, we estimated that the percentage decline in annual measles deaths was around 20% (90,043 of 454,000).

INTERPRETATION

The burden of measles in sub-Saharan Africa can be reduced to very low levels by means of appropriate strategies, resources, and personnel.

Sexual differences in onset of disease and response to exercise in a transgenic model of ALS

Transgenic mice that overexpress the mutant human SOD1 gene (hSOD1) serve as an animal model for amyotrophic lateral sclerosis (ALS). Age and sex are recognized as risk factors for ALS, but physical activity remains controversial. Therefore, we investigated the effect of exercise on the phenotype of male and female hSOD1 mice. Onset of disease, progression of disease and survival were measured in low-copy and high-copy hSOD1 mice that were randomized to an exercise or sedentary group. We found that onset of disease was different for the two sexes: significantly earlier in male than in female hSOD1 mice. Exercise delayed the onset of disease in female but not in male hSOD1 mice. Also, exercise delayed the total survival time in female high-copy hSOD1 mice. Muscle morphometry and motor neuron counts were similar in all experimental groups at the end of training. Sedentary female hSOD1 mice showed more frequently irregular estrous cycles suggesting a higher estrogen exposure in exercising female mice. These results suggest a possible neuroprotective effect of female sex hormones and support the view that ALS patients should not avoid regular exercise.

Progress towards polio eradication: an African perspective

Despite daunting competing health priorities, Africa has made significant progress in polio control. Northern and Southern Africa appear to be polio-free and may shortly be certified as such; however, polio still remains endemic in West and Central Africa and the Horn of Africa. Countries "in difficult circumstancess", wracked by major civil wars, have particularly low routine vaccine coverage, although NIDS have been carried out during negotiated days of tranquillity. AFP surveillance has also improved, although the quality of stool specimens is still far from ideal. There is, nevertheless, an extraordinary political commitment to the eradication campaign. Lessons from the history of polio in the continent need to be heeded in designing end-game strategies. Obstacles on the path to successful eradication are undoubtedly more formidable on the African continent--perhaps the most serious of all are the continuing wars. International political commitment and focussed and empowering developmental aid are urgently needed.

Massive outbreak of poliomyelitis caused by type-3 wild poliovirus in Angola in 1999

The largest outbreak of poliomyelitis ever recorded in Africa (1093 cases) occurred from 1 March to 28 May 1999 in Luanda, Angola, and in surrounding areas. The outbreak was caused primarily by a type-3 wild poliovirus, although type-1 wild poliovirus was circulating in the outbreak area at the same time. Infected individuals ranged in age from 2 months to 22 years; 788 individuals (72%) were younger than 3 years. Of the 590 individuals whose vaccination status was known, 23% had received no vaccine and 54% had received fewer than three doses of oral poliovirus vaccine (OPV). The major factors that contributed to this outbreak were as follows: massive displacement of unvaccinated persons to urban settings; low routine OPV coverage; inaccessible populations during the previous three national immunization days (NIDs); and inadequate sanitation. This outbreak indicates the urgent need to improve accessibility to all children during NIDs and the dramatic impact that war can have by displacing persons and impeding access to routine immunizations. The period immediately after an outbreak provides an enhanced opportunity to eradicate poliomyelitis. If continuous access in all districts for acute flaccid paralysis surveillance and supplemental immunizations cannot be assured, the current war in Angola may threaten global poliomyelitis eradication.

Awareness and attitudes concerning BRCA gene testing

BACKGROUND

The availability of a commercial test for the breast cancer susceptibility genes, BRCA1 and BRCA2, has generated interest in both the medical community and the general public.

METHODS

Patients and family members were approached in the waiting room and asked to fill out an anonymous questionnaire about their awareness of breast cancer genes and breast cancer gene testing, and their desire to be tested. chi2 analysis was used to analyze frequencies between groups.

RESULTS

A total of 354 women completed a questionnaire concerning the breast cancer genes BRCA1 and BRCA2. The very young, the very old, and African-Americans were the least informed in terms of awareness of the genes and the availability of testing for the breast cancer susceptibility genes. Jewish people, people with a college education or beyond, people earning more than $30,000 a year, and Caucasians were more aware of the genes and of testing for these genes. Interest in being tested was similar in all groups, except for participants over 60 and those who had only an elementary-school education.

CONCLUSIONS

Information concerning the breast cancer susceptibility genes has not reached the general public uniformly. A concerted effort is needed if this information is to be passed on to those people at risk.

Alginate regulatory and biosynthetic gene homologs in Pseudomonas putida WCS358: correlation with the siderophore regulatory gene pfrA

A previous study [Venturi et al., Mol. Microbiol. 10 (1993) 63-73] demonstrated that the siderophore regulatory gene pfrA of Pseudomonas putida (Pp) WCS358 is highly similar and interchangeable with the alginate regulatory gene algQ (algR2) of P. aeruginosa (Pa). The algQ gene is physically linked to two other alginate regulators in the Pa chromosome, namely algR (algR1), a response regulator, and algP (algR3), a histone-like gene. In this study, we have identified the same genes and a similar genetic organization in the Pp chromosome. The two genes linked to pfrA, designated pprA and pprB, are similar to algR and algP, respectively. Chromosomal mutants of pprA and pprB were constructed showing that unlike pfrA, the two newly identified regulators are not involved in siderophore regulation. The pprA gene complemented a Pa algR mutant phenotype, suggesting that it could be involved in alginate gene regulation. The WCS358 strain is not producing alginate, but we demonstrated by Southern analysis that it also possesses, in addition to pprA and pprB, algD and algU (algT) gene homologs, two genes essential for alginate biosynthesis. Using an algD-xylE transcriptional fusion, we observed that the algD promoter is active in strain WCS358 and absolutely requires pfrA. The possibility that all five genes of Pp WCS358 are involved in alginate biosynthesis is discussed.

Influence of thyroid function on theophylline kinetics

Theophylline kinetics were examined in five patients with hyperthyroidism before and after treatment with carbimazole. Theophylline clearance fell after carbimazole, but the apparent volume of distribution did not change. There was a correlation between reduction in theophylline clearance and decreased thyroxine serum concentration. Data suggest that maximum induction is reached at a specific level of thyroxine beyond which no further increase in drug metabolizing activity takes place. In 15 subjects treated with aminophylline for acute bronchial obstruction, there was a positive correlation between thyroxine concentration and total body theophylline clearance (r = 0.72 for nonsmokers; r = 0.44 for smokers and nonsmokers).

Increased mortality with cardiotoxic doses of Adriamycin after verapamil pretreatment despite prevention of myocardial calcium accumulation

The purpose of this investigation was to determine whether the calcium blocking agent, verapamil, could modify Adriamycin cardiotoxicity, and if so, whether or not such modification is mediated by a mechanism involving myocardial electrolyte distribution. The mean survival time of female New Zealand white rabbits administered Adriamycin was reduced by pretreatment with verapamil. Myocardial cellular calcium concentration, [Ca]i, in animals pretreated with verapamil before receiving Adriamycin was lower than in animals receiving Adriamycin alone (1.49 +/- 0.11 vs. 2.22 +/- 0.35 mmol/kg cell water, respectively; P = 0.05). Myocardial [Ca]i in control animals was 1.68 +/- 0.10 mmol/kg cell water. Myocardial [Mg]i in animals receiving Adriamycin alone was lower than that for animals receiving verapamil alone (15.6 +/- 1.4 vs. 19.2 +/- 0.8 mmol/kg cell water, respectively). When these drugs were combined, [Mg]i approached the control value of 17.3 +/- 0.06 mmol/kg cell water. Cellular concentrations of the monovalent electrolytes were little affected by these drugs, except for a reduction of [Cl]i by verapamil. Neither myocardial water distribution nor plasma concentrations of these electrolytes were altered by either drug. The data indicate that verapamil pretreatment increases the mortality associated with Adriamycin in rabbits despite the continued efficacy of verapamil as a Ca-blocking agent after injection of Adriamycin. Particular caution must be exercised if clinical combination of Ca-blocking agents and anthracyclines is contemplated.

Isolation of a DNA polymerase alpha-associated regulatory protein from calf thymus

A regulatory protein for DNA polymerase alpha, responsive to noncomplementary deoxyribonucleoside triphosphates, has been isolated from calf thymus. The regulatory protein was separated from DNA polymerase alpha using Affi-Gel Blue and gel filtration. The regulatory protein had a molecular weight of approximately 70,000 as determined by gel filtration, and its activity was nondialyzable, heat labile, and abolished by pronase treatment. In the presence of regulatory protein, DNA polymerase alpha activity, measured by using polydeoxyadenylate-oligodeoxythymidylate as template primer, was inhibited by 2'-deoxyguanosine 5'-triphosphate in a parabolic-competitive fashion [Ki = 15 +/- 1 (S.E.) microM] and by 2'-deoxycytidine 5'-triphosphate in a linear-competitive manner (Ki = 162 +/- 23 microM). Neither the four natural ribonucleoside triphosphates nor 2'-deoxyadenosine 5'-triphosphate inhibited the DNA polymerase-regulatory protein system to any significant extent. The regulatory protein by itself had no effect on either DNA polymerase alpha activity or the Km for template primer. These results indicate that deoxyribonucleoside triphosphate pools may be involved in the regulation of cellular DNA synthesis through a direct effect on DNA polymerization.

Evaluation of ribonucleoside and deoxyribonucleoside triphosphate pools in cultured leukemia cells during exposure to methotrexate or methotrexate plus thymidine

Continuous exposure to inhibitory concentrations of methotrexate produces distinct rates of steady-state growth of murine leukemia L1210 and human leukemia CCRF-CEM cells in culture. Addition of thymidine to the medium produces reversal (6 to 40%) of this steady-state growth rate inhibition. This study utilized combinations of methotrexate and thymidine for an evaluation of the accompanying relationship between steady-state growth rate and changes in the ribo- and deoxyribonucleoside triphosphate pools. In L1210 cells exposed to methotrexate alone, the deoxythymidine 5'-phosphate (dTTP) pools decreased, whereas deoxyadenosine 5'-triphosphate, deoxyguanosine 5'-triphosphate, and deoxycytidine 5'-triphosphate (dCTP) remained relatively constant up to 70% inhibition of growth rate, with dCTP at a constant 112% of controls. The corresponding ribonucleoside triphosphates decreased only slightly. With the combination of methotrexate and thymidine resulting in up to 40% inhibition of growth rate, there was also a decrease in the dTTP pool while the other deoxyribonucleoside triphosphates remained relatively constant, and the corresponding ribonucleoside triphosphates again decreased only slightly. The dCTP pool was reduced to a constant 42% of control comparable to that produced by thymidine alone. With greater than 40% (with thymidine) or 70% (without thymidine) inhibition of growth rate, all pools decreased, but only dTTP was substantially reduced in proportion to the growth rate inhibition caused by methotrexate. The dTTP pool became depleted in spite of the presence of exogenous thymidine. Evaluation of CCRF-CEM cells indicated that inhibition of growth rate and nucleotide pool perturbations by methotrexate were similar to those observed in L1210 cells. However, in the presence of thymidine, inhibition of growth rate appeared related to decreased pools of dCTP, deoxyadenosine 5'-triphosphate, and deoxyguanosine 5'-triphosphate, rather than dTTP as was observed for L1210 cells. Hence, mammalian cells were capable of responding in a differential fashion to pharmacological perturbations, and this capacity may play a role in determining therapeutic selectivity. Since the ribonucleoside triphosphate decreases were slight and relatively uniform during methotrexate-induced perturbations, the deoxyribonucleoside triphosphate pools appear to be more directly related to inhibition of growth rate. The results are consistent with the concept that slight imbalances in the deoxyribonucleoside triphosphate pools dramatically inhibit DNA synthesis, as mediated through their interaction with DNA polymerase.

Raised total thyroxine and free thyroxine index but normal free thyroxine. A serum abnormality due to inherited increased affinity of iodothyronines for serum binding protein

2 people from different families had high levels of serum-thyroxine (T4) and a high free T4 (FT4) index but a normal serum triiodothyronine (T3) and serum-reverse-T3 (rT3). The abnormal serum thyroid hormone profile appeared to be inherited in an autosomal dominant manner. Serum-FT4 in affected relatives was normal. The increases in serum-T4 and FT4 index are explained on the basis of an observed increase in affinity of T4 for thyroxine-binding globulin, thyroxine-binding prealbumin, and albumin. The FT4 index did not reflect the true concentration of circulating free T4 in these cases. Thyroid function in the propositi was normal and the results of T4, T3, and rT3 kinetic studies accorded with increased binding of T4 by serum proteins and normal binding of the other iodo-thyronines. This "euthyroid high total T4, normal T3 syndrome" should be kept in mind during diagnostic evaluation of thyroid function.

Induction of hepatic aryl hydrocarbon hydroxylase and epoxide hydrase in Wistar rats pretreated with oral methadone hydrochloride

Methadone-HCl added to the drinking water of adult female Wistar rats for 4 weeks produced an increase in the aryl hydrocarbon hydroxylase activity of the hepatic microsomal fraction to 222% of control levels. No change was seen in epoxide hydrase activity. In contrast, when male rats were treated similarly, there was an increase in epoxide hydrase activity to 212% of controls with no change in aryl hydrocarbon hydroxylase activity. No such changes were observed when the subcutaneous route of administration or chronic, low-dose, intraperitoneal injections were used. There were no differences in hepatic cytochrome P-450 or protein concentrations in treated animals as compared to their respective control groups. Control studies were carried out with quinine sulfate in the drinking water to decrease water intake to the level of the methadone-treated group. No elevation in either enzyme activity occurred in this control group. Similarly, paired-feeding studies showed the elevation of enzyme activity to be due to the methadone, not food deprivation. The effects of concurrent therapy of methadone with phenobarbital sodium or 3-methylcholanthrene were compared.

The effect of dieldrin-contaminated feed on rat hepatic microsomal epoxide hydrase and aryl hydrocarbon hydroxylase

Adult male rats were exposed to dieldrin-contaminated rations. The hydroxylation of benzpyrene (AHH) and hydration of styrene oxide (EH) by the hepatic microsomal fraction were followed. At dieldrin levels of 5 to 25 ppm for one week, the EH activity increased from 19% to 115% above control levels respectively. Animals exposed to 25 ppm developed elevated EH activities after a few days, with a maximum increase of 2.5 times control levels after two weeks. AHH activity was not elevated over control levels at any dose or time studied. Slight but significant increases in levels of cytochrome P-450 were observed. Pentobartibal sleeping time was decreased to 61% of control levels after exposure to 20 ppm dieldrin-contaminated food for 7 days. Two days of intraperitoneal administration of technical grade dieldrin, analytical grade dieldrin and analytical grade aldrin gave similar increases in EH activity within this group. Again, no changes in AHH activity were seen.