Materials and methods

Study design and conceptual framework

This study was designed as a prospective observational investigation aimed at characterizing the procedural and cognitive impact of obesity on forensic autopsy practice under standardized medico-legal conditions. The conceptual framework integrates three complementary dimensions: procedural workload, quantified through objective measurement of autopsy duration; cognitive performance, assessed via validated vigilance testing; and anatomical–technical complexity, evaluated through morphometric and qualitative observations (Fig. 1).

Fig. 1: Overview of study design and experimental workflow

The figure summarizes the prospective observational design, case selection criteria, standardized autopsy protocol, anthropometric assessment, objective measurement of autopsy duration, operator vigilance testing using the Mackworth Clock Test, evaluation of technical difficulty, and the statistical framework adopted to investigate BMI-related procedural and cognitive effects under controlled medico-legal conditions.

Case selection, eligibility criteria, and grouping

A total of 50 consecutive medico-legal autopsies performed for natural deaths at Institute of Legal Medicine of Magna Graecia University of Catanzaro were prospectively included. All participating operators provided informed consent for inclusion in the study. The study population was divided into two groups based on BMI: an obese cohort (n = 25) and a non-obese control group (n = 25). Inclusion in the obese cohort required a BMI ≥ 30 kg/m², while controls were defined by a BMI < 30 kg/m². The control group was selected to be comparable to the obese cohort with respect to age and sex distribution, in order to minimize demographic confounding. Exclusion criteria for both groups included advanced decomposition, extensive traumatic injuries, major post-surgical anatomical alterations, incomplete autopsy examinations, or the need for extraordinary investigative procedures that could independently prolong autopsy duration. Extraordinary procedures were defined as additional investigative steps beyond routine autopsy practice, including extensive toxicological sampling, radiological imaging (e.g., post-mortem CT), complex reconstruction procedures, or multidisciplinary interventions that could significantly prolong the examination time. Major post-surgical anatomical alterations included extensive prior surgical resections, anatomical reconstructions, or conditions significantly modifying normal organ relationships. Cases involving organ donation were also considered within this category and were therefore excluded. Although the specific causes of death were not completely uniform across cases, the study design minimized major procedural heterogeneity by excluding traumatic deaths, advanced decomposition, massive generalized edema, extensive surgical alterations, and other conditions potentially associated with unusually prolonged examinations. In addition, no evident imbalance in the distribution of major natural cause-of-death categories was observed between obese and control groups, reducing the likelihood that the observed differences in procedural duration were primarily driven by pathological variability rather than BMI-related anatomical complexity.

Anthropometric data collection and BMI classification

Body weight and height were directly measured in all cases prior to autopsy using standard mortuary procedures. When available, these measurements were cross-checked with recent antemortem clinical records. This approach was adopted to ensure accuracy in BMI estimation, taking into account potential post-mortem changes such as dehydration, which may affect body weight. [11, 12]. BMI was treated as both a continuous variable and a categorical variable in subsequent analyses. Within the obese cohort, cases were stratified into obesity class I (BMI 30.0–34.9 kg/m²), class II (BMI 35.0–39.9 kg/m²), and class III (BMI ≥ 40.0 kg/m²) according to internationally accepted thresholds, allowing exploration of dose–response relationships across increasing obesity severity. BMI classification was performed according to World Health Organization (WHO) guidelines [13–17].

Autopsy team composition and operator standardization

All autopsies were performed by the same fixed team consisting of a primary operator and a secondary operator, both experienced forensic pathologists with comparable training and years of practice. Maintaining a constant team composition was a deliberate methodological choice to minimize inter-operator variability in technical skill, speed, and fatigue susceptibility. The roles of primary and secondary operator were kept consistent across all cases, with the primary operator performing the core dissection and organ removal steps and the secondary operator assisting and documenting findings.

Procedural conditions and environmental control

All examinations were conducted in the same autopsy suite during routine institutional activity from Monday to Friday, between 07:00 and 12:00. No autopsies included in the study were performed during night shifts or public holidays. This time window was selected to reduce circadian influences on attention, alertness, and fatigue, which are known to affect cognitive performance. Although the specific weekday was not analyzed as an independent variable, the distribution of cases across the regular working week reduced the likelihood of systematic bias related to accumulated operator fatigue. Environmental parameters such as lighting, room temperature, and workspace organization were maintained as constant as possible throughout the study period. Both obese cases and controls were examined under identical procedural and environmental conditions, ensuring that differences in duration or vigilance were not attributable to extrinsic factors.

Standardized autopsy protocol

A uniform autopsy protocol was strictly applied to all cases. Cranial access was achieved through a bi-mastoid incision with removal of the calvarium and routine brain extraction. Thoracic and abdominal cavities were opened using a Y-shaped incision. Complete evisceration of thoracic and abdominal organs was performed in all cases, followed by fresh gross examination and systematic sectioning of all organs. The heart was consistently removed en bloc and subjected to systematic fresh dissection during the autopsy, followed by fixation in formaldehyde for subsequent detailed examination. Also, the remaining organs were examined fresh according to institutional routine practice. No deviations from this protocol were permitted, and no procedural shortcuts were allowed, even in technically challenging cases, in order to preserve methodological comparability.

Measurement and operationalization of autopsy duration

Autopsy duration was measured objectively in minutes using a standardized timing protocol. The start time was defined as the moment of the first skin incision, and the end time corresponded to completion of organ removal and sectioning, immediately prior to reconstruction of the body. Autopsy duration was analyzed as a continuous variable and additionally categorized into duration intervals to explore nonlinear associations with vigilance decrement.

Vigilance assessment and Mackworth Clock Test protocol

Operator vigilance was assessed using the Mackworth Clock Test, a validated and widely used paradigm for evaluating sustained attention and vigilance decrement during prolonged tasks. The test was administered individually to both the primary and secondary operators immediately before the start of each autopsy and immediately after its completion. Each testing session lasted five minutes and involved continuous monitoring of a rotating clock hand, during which infrequent critical events, operationally defined as double jumps of the second hand, occurred at irregular intervals. Operators were instructed to respond to each critical event via a standardized input mechanism. The number of missed critical stimuli was recorded as the primary vigilance outcome. Vigilance decrement was operationalized as the difference between post-autopsy and pre-autopsy test performance, allowing within-subject control for baseline attentional variability.

Morphometric assessment of adipose tissue and technical observations

Morphometric assessment of subcutaneous adipose tissue thickness was performed at the thoracoabdominal incision site during each autopsy, providing an objective anatomical parameter related to dissection difficulty [11, 12]. Particular attention was paid to cases with higher BMI values. In parallel, technical difficulty was qualitatively documented throughout the procedure, focusing on exposure, mobilization, and removal of anatomically deep or adipose-surrounded organs, including the liver, pancreas, adrenal glands, and pelvic organs. Technical observations included the need for extended incision depth, delayed access to body cavities, prolonged mobilization maneuvers, and increased manipulation of perivisceral adipose tissue.

Statistical analysis and modeling strategy

Descriptive statistics were used to summarize demographic, anthropometric, procedural, and vigilance-related variables, expressed as mean ± standard deviation and range as appropriate. Distributional properties were assessed prior to inferential analysis to guide the choice of parametric or non-parametric methods. Between-group comparisons between obese cases and controls were conducted using appropriate statistical tests based on data distribution. Associations between BMI and autopsy duration were explored using correlation analysis and linear regression modeling, with BMI entered as a continuous predictor. Regression models were adjusted for age and sex to assess potential confounding.

To evaluate the relationship between procedural workload and cognitive performance, vigilance decrement was modeled as a function of autopsy duration using linear regression. An indirect-effect analytical framework was applied to assess whether the effect of BMI on vigilance decrement was mediated by procedural duration. Given the exploratory nature of the vigilance-related analyses and the moderate sample size, findings should be interpreted cautiously and considered hypothesis-generating. All analyses were conducted in accordance with accepted biostatistical standards for exploratory forensic and human-factors research.