Brain networks of temporal preparation: A multiple regression analysis of neuropsychological data.

There are only a few studies on the brain networks involved in the ability to prepare in time, and most of them followed a correlational rather than a neuropsychological approach. The present neuropsychological study performed multiple regression analysis to address the relationship between both grey and white matter (measured by magnetic resonance imaging in patients with brain lesion) and different effects in temporal preparation (Temporal orienting, Foreperiod and Sequential effects). Two versions of a temporal preparation task were administered to a group of 23 patients with acquired brain injury. In one task, the cue presented (a red versus green square) to inform participants about the time of appearance (early versus late) of a target stimulus was blocked, while in the other task the cue was manipulated on a trial-by-trial basis. The duration of the cue-target time intervals (400 versus 1400ms) was always manipulated within blocks in both tasks. Regression analysis were conducted between either the grey matter lesion size or the white matter tracts disconnection and the three temporal preparation effects separately. The main finding was that each temporal preparation effect was predicted by a different network of structures, depending on cue expectancy. Specifically, the Temporal orienting effect was related to both prefrontal and temporal brain areas. The Foreperiod effect was related to right and left prefrontal structures. Sequential effects were predicted by both parietal cortex and left subcortical structures. These findings show a clear dissociation of brain circuits involved in the different ways to prepare in time, showing for the first time the involvement of temporal areas in the Temporal orienting effect, as well as the parietal cortex in the Sequential effects.

Temporal orienting deficit after prefrontal damage.

The aim of this study was to explore, for the first time in patients, the neural bases of temporal orienting of attention as well as the interrelations with two other effects of temporal preparation: the foreperiod effect and sequential effects. We administered an experimental task to a group of 14 patients with prefrontal lesion, a group of 15 control subjects and a group of 7 patients with a basal ganglia lesion. In the task, a cue was presented (a short versus long line) to inform participants about the time of appearance (early versus late) of a target stimulus, and the duration of the cue-target time intervals (400 versus 1400 ms) was manipulated. In contrast to the control group, patients with right prefrontal lesion showed a clear deficit in the temporal orienting effect. The foreperiod effect was also affected in the group of patients with prefrontal lesion (without lateralization of the deficit), whereas sequential effects were preserved. The group of basal ganglia patients did not show deficits in any of the effects. These findings support the voluntary and strategic nature of the temporal orienting and foreperiod effects, which depend on the prefrontal cortex, as well as the more automatic nature of sequential effects, which do not depend on either prefrontal cortex or frontobasal circuits.

Temporal preparation and inhibitory deficit in fibromyalgia syndrome.

Cognitive deficits in fibromyalgia may be specifically related to controlled processes, such as those measured by working memory or executive function tasks. This hypothesis was tested here by measuring controlled temporal preparation (temporal orienting) during a response inhibition (go no-go) task. Temporal orienting effects (faster reaction times for targets appearing at temporally attended vs. unattended moments) and response inhibition were impaired in fibromyalgia compared to the control group. It is concluded that frontal networks underlying attentional control (temporal orienting and response inhibition) can be a dysfunctional neurocognitive mechanism in fibromyalgia.

Temporal preparation, response inhibition and impulsivity.

Temporal preparation and impulsivity involve overlapping neural structures (prefrontal cortex) and cognitive functions (response inhibition and time perception), however, their interrelations had not been investigated. We studied such interrelations by comparing the performance of groups with low vs. high non-clinical trait impulsivity during a temporal preparation go no-go task. This task measured, in less than 10 min, how response inhibition was influenced both by temporal orienting of attention (guided by predictive temporal cues) and by sequential effects (produced by repetition/alternation of the duration of preparatory intervals in consecutive trials). The results showed that sequential effects produced dissociable patterns of temporal preparation as a function of impulsivity. Sequential effects facilitated both response speed (reaction times - RTs - to the go condition) and response inhibition (false alarms to the no-go condition) selectively in the low impulsivity group. In the high impulsivity group, in contrast, sequential effects only improved RTs but not response inhibition. We concluded that both excitatory and inhibitory processing may be enhanced concurrently by sequential effects, which enables the temporal preparation of fast and controlled responses. Impulsivity could hence be related to less efficient temporal preparation of that inhibitory processing.

Circadian rhythms and decision-making: a review and new evidence from electroencephalography.

Since emotions and regulatory control are relevant for decision-making, their circadian fluctuation should influence the outcome of such decisions, but this question has been rarely addressed. A review of the literature suggests that the evidence regarding circadian synchrony effects (better performance at optimal vs. non-optimal times of day according to chronotype) on decision-making is mixed, likely due to the use of different approaches to estimate chronotype. The current experiment studied economic decision-making as a function of both chronotype and the time of day when decisions are made. The influence of chronotype (Morning-type: N = 28 vs. Evening-type: N = 30) and time of day (8 am vs. 10 pm) on decision-making was measured by the acceptance rate of unfair and fair offers in the Ultimatum Game, and the event-related potentials time-locked to such offers. Subjective affect (PANAS), and appraisal of emotional images (IAPS) were also measured. Chronotype was estimated through questionnaires (MEQ, rMEQ, MCTQ) and the circadian rhythm of wrist temperature. Synchrony effects were found for both wrist temperature and subjective affect, but not for behavioral performance. Morning-types showed earlier phases of circadian rhythms in temperature, reported better sleep quality, more positive affective balance, accepted more unfair offers, and their frontal P200 potential was attenuated as compared to Evening-types in the Ultimatum Game. Acceptance rate of unfair offers correlated with the chronotype measured by questionnaires (positive correlation with rMEQ and MEQ scores, and negative correlation with Midsleep time in workdays -MSWsc from MCTQ) but not with midsleep time estimated through wrist temperature. Finally, participants who accepted more unfair offers later judged positive IAPS stimuli as more pleasant. We did not observe a synchrony effect in the Ultimatum Game, but morningness was related to rational decision-making as indexed by increased acceptance of unfair offers. Since morning-types show higher emotional regulation and positive mood than evening-types, it is possible that unfair offers did not elicit negative emotions as intense in morning-types as in evening-types, making it easier for them to accept.Abbreviations: ACC: anterior cingulate cortex; ANOVA: analysis of variance; BART: Balloon Analogue Risk Task; DLPFC: dorsolateral prefrontal cortex; EEG: electroencephalography; IAPS: International Affective Picture System; ICA: Independent component analysis; KSS: Karolinska Sleepiness Scale; LPP: Late Positive Potential; M: mean; MCTQ: Munich Chronotype Questionnaire; MEQ: Morningness Eveningness Questionnaire; MFN: Medial Frontal Negativity; MSWsc: midsleep time for working days corrected for sleep debt; MSFsc: midsleep time for free days corrected for sleep debt; N: number of participants; PANAS: Positive and Negative Affect Schedule; PSQI: Pittsburgh Sleep Quality Index; PVT: Psychomotor Vigilance Task; rMEQ: reduced Morningness Eveningness Questionnaire; RNA: Ribonucleic acid; RT: reaction time; SAM: Self-Assessment Manikin; SD: standard deviation; UG: Ultimatum Game.

CoVidAffect, real-time monitoring of mood variations following the COVID-19 outbreak in Spain.

The COVID-19 outbreak and the ensuing confinement measures are expected to bear a significant psychological impact on the affected populations. To date, all available studies designed to investigate the psychological effects of this unprecedented global crisis are based on cross-sectional surveys that do not capture emotional variations over time. Here, we present the data from CoVidAffect, a nationwide citizen science project aimed to provide longitudinal data of mood changes following the COVID-19 outbreak in the spanish territory. Spain is among the most affected countries by the pandemic, with one of the most restrictive and prolonged lockdowns worldwide. The project also collected a baseline of demographic and socioeconomic data. These data can be further analyzed to quantify emotional responses to specific measures and policies, and to understand the effect of context variables on psychological resilience. Importantly, to our knowledge this is the first dataset that offers the opportunity to study the behavior of emotion dynamics in a prolonged lockdown situation.

Electroencephalographic and peripheral temperature dynamics during a prolonged psychomotor vigilance task.

Attention lapses and fatigue are a main source of impaired performance that can lead to accidents. This study analyzed electroencephalographic (EEG) dynamics and body skin temperature as markers of attentional fluctuations in non-sleep deprived subjects during a 45min Psychomotor Vigilance Task (PVT). Independent Component Analysis and time-frequency analysis were used to evaluate the EEG data. Results showed a positive association between distal and distal-to-proximal gradient (DPG) temperatures and reaction time (RT); increments in EEG power in alpha-, theta- and beta-band frequencies in parieto-occipital, central-medial and frontal components, were associated with poor performance (slower RT) in the task. This generalized power increment fits with an increased activity in the default mode network, associated with attention lapses. This study highlights the potential use of the PVT as a tool to obtain individual physiological indices of vigilance and fatigue that could be applied to other vigilance tasks typically performed in occupational settings.

Application of Machine Learning Methods to Ambulatory Circadian Monitoring (ACM) for Discriminating Sleep and Circadian Disorders.

The present study proposes a classification model for the differential diagnosis of primary insomnia (PI) and delayed sleep phase disorder (DSPD), applying machine learning methods to circadian parameters obtained from ambulatory circadian monitoring (ACM). Nineteen healthy controls and 242 patients (PI = 184; DSPD = 58) were selected for a retrospective and non-interventional study from an anonymized Circadian Health Database (https://kronowizard.um.es/). ACM records wrist temperature (T), motor activity (A), body position (P), and environmental light exposure (L) rhythms during a whole week. Sleep was inferred from the integrated variable TAP (from temperature, activity, and position). Non-parametric analyses of TAP and estimated sleep yielded indexes of interdaily stability (IS), intradaily variability (IV), relative amplitude (RA), and a global circadian function index (CFI). Mid-sleep and mid-wake times were estimated from the central time of TAP-L5 (five consecutive hours of lowest values) and TAP-M10 (10 consecutive hours of maximum values), respectively. The most discriminative parameters, determined by ANOVA, Chi-squared, and information gain criteria analysis, were employed to build a decision tree, using machine learning. This model differentiated between healthy controls, DSPD and three insomnia subgroups (compatible with onset, maintenance and mild insomnia), with accuracy, sensitivity, and AUC >85%. In conclusion, circadian parameters can be reliably and objectively used to discriminate and characterize different sleep and circadian disorders, such as DSPD and OI, which are commonly confounded, and between different subtypes of PI. Our findings highlight the importance of considering circadian rhythm assessment in sleep medicine.

Spatial and temporal acuity of visual perception can be enhanced selectively by attentional set.

The aim of this research was to study the relationship between perceptual judgments about space and time. If spatial and temporal judgments were dissociable, they should be modulated selectively by attention. We compared the effect of the attentional set upon fine-grained spatial versus temporal discrimination of visual perception in two experiments. Using identical sensory stimulation, we measured perceptual judgments on either the size of a small spatial gap or the duration of a brief temporal gap. The attentional set was manipulated by cuing the task that was most likely to be performed. In one experiment, a neutral cue was also used, to measure relative benefits and costs of spatial and temporal task sets. If the attentional set could be directed selectively to spatial and temporal task-relevant dimensions, performance on both spatial and temporal acuity tasks should be specifically modulated by task cuing. The results showed that the attentional set enhanced the speed and accuracy of perceptual judgments similarly on both spatial and temporal tasks. Moreover, accuracy in one task was selectively enhanced by attending to that task while remaining unaffected by attending to the alternative task. This finding suggests multiple mechanisms, by which visual processing of spatial and temporal features can be selectively prepared without interfering with one another.

Dissociating Explicit and Implicit Timing in Parkinson's Disease Patients: Evidence from Bisection and Foreperiod Tasks.

A consistent body of literature reported that Parkinson's disease (PD) is marked by severe deficits in temporal processing. However, the exact nature of timing problems in PD patients is still elusive. In particular, what remains unclear is whether the temporal dysfunction observed in PD patients regards explicit and/or implicit timing. Explicit timing tasks require participants to attend to the duration of the stimulus, whereas in implicit timing tasks no explicit instruction to process time is received but time still affects performance. In the present study, we investigated temporal ability in PD by comparing 20 PD participants and 20 control participants in both explicit and implicit timing tasks. Specifically, we used a time bisection task to investigate explicit timing and a foreperiod task for implicit timing. Moreover, this is the first study investigating sequential effects in PD participants. Results showed preserved temporal ability in PD participants in the implicit timing task only (i.e., normal foreperiod and sequential effects). By contrast, PD participants failed in the explicit timing task as they displayed shorter perceived durations and higher variability compared to controls. Overall, the dissociation reported here supports the idea that timing can be differentiated according to whether it is explicitly or implicitly processed, and that PD participants are selectively impaired in the explicit processing of time.

The Role of Exercise-Induced Arousal and Exposure to Blue-Enriched Lighting on Vigilance.

It is currently assumed that exposure to an artificial blue-enriched light enhances human alertness and task performance, but recent research has suggested that behavioral effects are influenced by the basal state of arousal. Here, we tested whether the effect of blue-enriched lighting on vigilance performance depends on participants' arousal level. Twenty-four participants completed four sessions (blue-enriched vs. dim light × low vs. high arousal) at 10 pm on four consecutive days, following a repeated-measures design. Participants' arousal was manipulated parametrically through the execution of a cycling task at two intensities (low vs. moderate), and was checked by monitoring their heart rate. On each session, distal and proximal skin temperatures were recorded as a neuroergonomic index of vigilance, while participants performed a 20-min psychomotor vigilance task (PVT) under either blue-enriched light or dim light conditions. The Positive and Negative Affect Schedule (PANAS), Karolinska Sleepiness Scale (KSS), and Borg Rating of Perceived Exertion Scale (RPE) were used to measure subjective psychological state. The results showed that the exercise-induced manipulation of arousal produced robust alerting effects in most measures, while the lighting manipulation only attenuated subjective sleepiness and enhanced positive affect, but it did not influence behavior or physiology. Acute exposure to a blue-enriched light was practically ineffective when the arousal level was over baseline. The present research favored the use of acute physical exercise over acute exposure to blue-enriched lighting in order to boost humans' alertness when necessary, as in work settings where maintaining optimal levels of attention is difficult (shift work, night-work, vigilance tasks) and necessary to prevent human error and accidents.

Blue-Enriched Light Enhances Alertness but Impairs Accurate Performance in Evening Chronotypes Driving in the Morning.

Attention maintenance is highly demanding and typically leads to vigilance decrement along time on task. Therefore, performance in tasks involving vigilance maintenance for long periods, such as driving, tends to deteriorate over time. Cognitive performance has been demonstrated to fluctuate over 24 h of the day (known as circadian oscillations), thus showing peaks and troughs depending on the time of day (leading to optimal and suboptimal times of day, respectively). Consequently, vigilance decrements are more pronounced along time on task when it is performed at suboptimal times of day. According to research, light exposure (especially blue-enriched white) enhances alertness. Thus, it has been proposed to prevent the vigilance decrement under such adverse circumstances. We aimed to explore the effects of blue-enriched white light (vs. dim light) on the performance of a simulated driving task at a suboptimal time of day. A group of evening-types was tested at 8 am, as this chronotype had previously shown their largest vigilance decrement at that time. In the dim light condition, vigilance decrements were expected on both subjective (as increments in the Karolinska Sleepiness Scale scores) and behavioral measures [as slower reaction times (RTs) in the auditory Psychomotor Vigilance Task, slower RTs to unexpected events during driving, and deteriorated driving accuracy along time on task]. Physiological activation was expected to decrease (as indexed by an increase of the distal-proximal temperature gradient, DPG). Under blue-enriched white light, all these trends should be attenuated. Results from the control dim light condition replicated the vigilance decrement in all measures. Most important, the blue-enriched white light attenuated this decrement, leading to both lower DPG and faster RTs. However, it impaired accuracy of driving performance, and did not have any effect on subjective sleepiness. We conclude that exposure to blue-enriched light provides an effective countermeasure to enhance vigilance performance at suboptimal times of day, according to measures such as RTs. However, it should be considered that alerting effects of light could impair accuracy in precision tasks as keeping a proper car position. The current findings provide ergonomic implications for safety and fatigue related management systems.

Blue-Enriched White Light Enhances Physiological Arousal But Not Behavioral Performance during Simulated Driving at Early Night.

Vigilance usually deteriorates over prolonged driving at non-optimal times of day. Exposure to blue-enriched light has shown to enhance arousal, leading to behavioral benefits in some cognitive tasks. However, the cognitive effects of long-wavelength light have been less studied and its effects on driving performance remained to be addressed. We tested the effects of a blue-enriched white light (BWL) and a long-wavelength orange light (OL) vs. a control condition of dim light on subjective, physiological and behavioral measures at 21:45 h. Neurobehavioral tests included the Karolinska Sleepiness Scale and subjective mood scale, recording of distal-proximal temperature gradient (DPG, as index of physiological arousal), accuracy in simulated driving and reaction time in the auditory psychomotor vigilance task. The results showed that BWL decreased the DPG (reflecting enhanced arousal), while it did not improve reaction time or driving performance. Instead, blue light produced larger driving errors than OL, while performance in OL was stable along time on task. These data suggest that physiological arousal induced by light does not necessarily imply cognitive improvement. Indeed, excessive arousal might deteriorate accuracy in complex tasks requiring precision, such as driving.

"Lost in time" but still moving to the beat.

Motor synchronization to the beat of an auditory sequence (e.g., a metronome or music) is widespread in humans. However, some individuals show poor synchronization and impoverished beat perception. This condition, termed "beat deafness", has been linked to a perceptual deficit in beat tracking. Here we present single-case evidence (L.A. and L.C.) that poor beat tracking does not have to entail poor synchronization. In a first Experiment, L.A., L.C., and a third case (L.V.) were submitted to the Battery for The Assessment of Auditory Sensorimotor and Timing Abilities (BAASTA), which includes both perceptual and sensorimotor tasks. Compared to a control group, L.A. and L.C. performed poorly on rhythm perception tasks, such as detecting time shifts in a regular sequence, or estimating whether a metronome is aligned to the beat of the music or not. Yet, they could tap to the beat of the same stimuli. L.V. showed impairments in both beat perception and tapping. In a second Experiment, we tested whether L.A., L.C., and L.V.'s perceptual deficits extend to an implicit timing task, in which they had to respond as fast as possible to a different target pitch after a sequence of standard tones. The three beat-deaf participants benefited similarly to controls from a regular temporal pattern in detecting the pitch target. The fact that synchronization to a beat can occur in the presence of poor perception shows that perception and action can dissociate in explicit timing tasks. Beat tracking afforded by implicit timing mechanisms is likely to support spared synchronization to the beat in some beat-deaf participants. This finding suggests that separate pathways may subserve beat perception depending on the explicit/implicit nature of a task in a sample of beat-deaf participants.

Economic decision-making in morning/evening-type people as a function of time of day.

Decision-making is affected by psychological factors like emotional state or cognitive control, which may also vary with circadian rhythmicity. Here, we tested the influence of chronotype (32 morning-type versus 32 evening-type) and time of day (9 a.m. versus 5 p.m.) on interpersonal decision-making as measured by the Ultimatum Game. Participants had to accept or reject different economic offers proposed by a virtual participant. Acceptance involved distribution of gains as proposed, whereas rejection resulted in no gain for either player. The results of the game showed a deviation from rational performance, as participants usually rejected the unfair offers. This behaviour was similar for both chronotype groups, and in both times of day. This result may reflect the robustness of decision-making strategies across standard circadian phases under ecological conditions. Furthermore, morning-types invested more time than evening-types to respond to high-uncertainty offers. This more cautious decision-making style of morning-types fits with our finding of higher proactive control as compared to evening-types when performing the AX-Continuous Performance Task. In line with the literature on personality traits, our results suggest that morning-types behave with more conscientiousness and less risk-taking than evening-type individuals.

Pitiriasis rosada como manifestación dermatológica de infección por SARS-CoV-2: a propósito de un caso / Pityriasis rosea as a cutaneous manifestation associated with SARS-CoV-2 infection: case report

Las manifestaciones cutáneas relacionadas a la infección por el coronavirus SARS-CoV-2, causante de COVID-19, se han descrito entre el 0,2% y 20,4% de las personas que cursan con esta enfermedad. Las más frecuentemente descritas son: lesiones maculopapulares (47%), lesiones acrales eritematosas con vesículas o pústulas (pseudoperniosis) (19%), urticariales (19%), lesiones vesiculosas (9%) y livedo/necrosis (6%). En particular, la pitiriasis rosada es una dermatosis autolimitada de etiología desconocida, sin embargo, se ha visto asociada a la infección por SARS-CoV-2, con algunos reportes de casos en la literatura. El mecanismo fisiopatológico de las lesiones cutáneas en COVID-19 no es claro, y se han planteado algunas teorías, entre las cuales está el papel que juega la enzima convertidora de angiotensina 2 (ACE2) utilizada por el virus para infectar las células, los infiltrados linfocíticos, los depósitos de factores del complemento en la piel, y la reactivación de virus latentes como los herpes virus humanos. Se presenta el caso de una paciente con pitiriasis rosada asociada a COVID-19 y se describen los casos reportados hasta la fecha

Temporal attention enhances early visual processing: a review and new evidence from event-related potentials.

Two fundamental cognitive functions, selective attention and processing of time, have been simultaneously explored in recent studies of temporal orienting of attention. A temporal-orienting procedure may consist of a temporal analogue to the Posner's paradigm, such that symbolic cues indicate the most probable moment for target arrival. Behavioral measures suggest that performance is improved for events appearing at expected vs. unexpected moments. However, there is no agreement on the locus of stimulus processing at which temporal attention operates. Thus, it remains unclear whether early perceptual or just late motor processes can be modulated. This article reviews current ERP research on temporal orienting, with an emphasis on factors that might determine the modulation of temporal orienting at early stages of processing. We conclude that: First, late components (N2 and P300) are consistently modulated by temporal orienting, which suggests attentional preparation of decision and/or motor processes. Second, early components (e.g., N1) seem to be modulated only when the task is highly demanding in perceptual processing. Hence, we conducted an ERP experiment which aimed to observe a modulation of early visual processing by using a perceptually demanding task, such as letter discrimination. The results show, for the first time, that targets appearing at attended moments elicited a larger P1 component than unattended targets. Moreover, temporal attention modulated the amplitude and latency of N2 and P300 components. This suggests that temporal orienting of attention not only modulates late motor processing, but also early visual processing when perceptually demanding tasks are used.

Selective temporal attention enhances the temporal resolution of visual perception: Evidence from a temporal order judgment task.

We investigated whether attending to a particular point in time affects temporal resolution in a task in which participants judged which of two visual stimuli had been presented first. The results showed that temporal resolution can be improved by attending to the relevant moment as indicated by the temporal cue. This novel finding is discussed in terms of the differential effects of spatial and temporal attention on temporal resolution.

Light Effects on Behavioural Performance Depend on the Individual State of Vigilance.

Research has shown that exposure to bright white light or blue-enriched light enhances alertness, but this effect is not consistently observed in tasks demanding high-level cognition (e.g., Sustained Attention to Response Task-SART, which measures inhibitory control). Individual differences in sensitivity to light effects might be mediated by variations in the basal level of arousal. We tested this hypothesis by measuring the participants' behavioural state of vigilance before light exposure, through the Psychomotor Vigilance Task. Then we compared the effects of a blue-enriched vs. dim light at nighttime on the performance of the auditory SART, by controlling for individual differences in basal arousal. The results replicated the alerting effects of blue-enriched light, as indexed by lower values of both proximal temperature and distal-proximal gradient. The main finding was that lighting effects on SART performance were highly variable across individuals and depended on their prior state of vigilance. Specifically, participants with higher levels of basal vigilance before light exposure benefited most from blue-enriched lighting, responding faster in the SART. These results highlight the importance of considering basal vigilance to define the boundary conditions of light effects on cognitive performance. Our study adds to current research delineating the complex and reciprocal interactions between lighting effects, arousal, cognitive task demands and behavioural performance.

Factores tempranos asociados a apendicectomía negativa / Early factors associated with negative appendectomy

Objetivo: analizar características predictoras de apendicectomía negativa (AN) en una cohorte de pacientes llevados a cirugía durante el año 2018 en una institución de salud de alta complejidad de la ciudad de Medellín, Colombia. Materiales y Métodos: seguimiento retrospectivo a una cohorte basada en registros médicos. Se analizaron pacientes adultos sometidos a apendicectomía. Se estimó la tasa de AN y se describieron características clínicas, paraclínicas y sociodemográficas. Se analizaron predictores de AN mediante el modelo lineal generalizado familia binomial, enlace logarítmico. Se presentan razones de riesgo (RR) observadas y ajustadas junto con intervalos de confianza del 95% (IC95%). Para el modelo multivariado se estimó el área bajo la curva del operador receptor (ROC). Resultados: la tasa de AN fue de 5,2%. No se solicitó tomografía computarizada (TC) de abdomen en el 48,9% de los casos, 4,1% de los pacientes presentaron disuria. Entre los factores estudiados, la disuria, no solicitud de TC, edad y leucocitosis, se asociaron significativamente con mayor riesgo de AN. Resaltan particularmente los pacientes que presentaron disuria y no les fue solicitado TC, en quienes el riesgo ajustado de AN fue de 30,3% (RR = 17,31; IC95% 5,00 ­ 59,87). ROC fue 0,834. Conclusiones: los pacientes llevados a cirugía sin TC y que se presentaron con disuria, particularmente los de mayor edad, concentraron el mayor riesgo de AN. Considerar estas características al definir el manejo quirúrgico del paciente con sospecha de apendicitis aguda, puede contribuir a disminuir las AN..(Au)

Objective: to analyze predictive characteristics of negative appendectomy (NA) in a cohort of patients who underwent surgery during 2018 in a high complexity healthcare institution in the city of Medellín, Colombia. Materials and Methods: retrospective follow-up to a cohort of adult patients who underwent appendectomy. The rate of NA was estimated and the clinical, paraclinical and sociodemographic characteristics were described. The analysis of predictors of NA was carried out using the generalized linear model binomial family, logarithmic link. Observed and adjusted risk ratios (RR) are presented along with 95% confidence intervals (95% CI). For the multivariate model, the area under the receiver operator curve (ROC) was estimated. Results: the NA rate was 5.2%. Abdominal computed tomography (CT) was not requested in 48.9% of the cases, 4.1% of the patients had dysuria. Among the factors studied, dysuria, nonrequest for CT, age and leukocytosis were significantly associated with a higher risk of NA. Is worth noting that the adjusted risk of NA of the patients who presented with dysuria and those in which no CT was requested, was 30.3% (RR = 17.31; 95% CI 5.00 - 59.87). ROC was 0.834. Conclusions: patients who underwent surgery without CT and presented with dysuria, particularly the older ones, had the highest risk of NA. Considering these characteristics when defining the surgical management of patients with suspected acute appendicitis can help reduce NA..(Au)