Assessing tuberculosis in the skeleton with the use of decision tree analysis.

Diagnosis of specific infectious diseases in the skeleton is often difficult and relies on expert opinion. Statistics is not often used as a tool to assist in such diagnoses, and therefore this study aimed at employing data mining and machine learning in the form of decision tree analysis to aid in recognizing tuberculosis (TB) in skeletal remains and find patterns of skeletal involvement. The sample included 387 modern South African individuals (n = 207 individuals known to have died of TB and n = 180 as a control group) which were scored for the presence or absence of 21 skeletal lesions documented to be associated with TB. A pruned decision tree classification analysis was done to detect significant patterns and associations between variables which produced a model with a moderate classification rate based on four of the variables. As expected, vertebral changes were selected first, followed by rib, acetabular and lastly cranial changes. As a proof of concept, it was shown that machine learning was able to identify patterns of changes in TB skeletons versus a control group. However, further investigation into the use of machine learning in assessing skeletal changes associated with specific diseases is needed.

Cribra orbitalia: Prevalence in contemporary populations.

The prevalence of cribra orbitalia (CO) is often used as an indicator of the general health status of past populations. Although debates as to its exact etiology are still ongoing, cribra is generally accepted to be the result of an anemic condition. Cribra has been reported to be declining in modern populations or even to be absent. The aim of this study was to compare modern, historic, and prehistoric prevalences of CO to assess whether it has changed through time and if it still occurs in contemporary populations. CO in skeletons (n = 844) from two widely different regions, the northeastern US and the central Gauteng area of South Africa, were compared in order to evaluate temporal trends. The sample comprised 245 prehistoric, 381 historic, and 218 modern skeletons. In adult skeletons the prevalence was found to be lower in historic South Africans (2.23%) than in historic North Americans (6.25%). It was lower in modern North Americans than in modern South Africans (12.35 and 16.8%, respectively). Its prevalence in prehistoric North Americans (11.86%) was also not much different from that of modern North Americans (12.35%). The frequency of CO in historic South African juveniles was higher (10.71%) than in historic North American juveniles (1.35%). Modern South African children had a lower frequency (25.14%) than modern American juveniles (40%), although the sample in the North American group was small. It seems that CO is still present in modern populations, and that health may indeed have declined for some groups in recent times. Clin. Anat. 29:823-830, 2016. © 2016 Wiley Periodicals, Inc.

Evaluating the Accuracy of Cranial Indices in Ancestry Estimation Among South African Groups.

Historically, population differences were quantified using cranial indices. Even though the application of indices is associated with numerous statistical and methodological problems, the use of cranial indices to estimate ancestry persists as demonstrated by its inclusion in several recent papers and conference presentations. The purpose of this study was to classify 207 South African crania and compare the results of five standard cranial indices to linear discriminant analysis (LDA). New sectioning points were created to contend with low classification accuracies (40-79%) and possible secular trends. Although the accuracies of the new sectioning points increased (66-87%), the accuracies associated with the stepwise LDA were higher (84%) and could classify the crania into one of the three South African groups. The results of the study demonstrate that indices cannot compete with multivariate techniques and should not be used in forensic anthropological analyses for ancestry estimation.

The changing face of tuberculosis: trends in tuberculosis-associated skeletal changes.

Tuberculosis remains a major health problem in many areas of the world. Previous research suggested that the frequency of bone lesions has decreased in the modern (but pre-antibiotic) period, and that the predominantly spinal involvement have changed to affect other parts of the skeleton, in particular ribs. The purpose of this study was to investigate whether bone lesions associated with TB became more or less common in the post-antibiotic period, and if the pattern of skeletal involvement has changed. The skeletons of 147 individuals from South Africa who died from TB were assessed. These were divided into three groups - those dying before 1950 and presumed to have had no antibiotic intervention (n = 52); those dying between 1950 and 1985 presumed to have been treated with antibiotics (n = 34); and those dying after 1985 where co-infection with HIV and drug-resistant disease emerged (n = 61). Overall, 33.3% of all individuals showed signs that could be associated with TB, with corresponding figures in each of the three groups being 21.1%, 38.2% and 41.0%. The increase from group 1 to 3 was statistically significant. Rib lesions are becoming more common, while spinal lesions are decreasing. It may be suggested that patients are surviving for longer due to antibiotic treatment, allowing more time for the development of lesions.