Is HbA1c a good screening test for diabetes mellitus?

Different Trajectories for Diabetes Mellitus Onset and Recovery According to the Centralized Aerobic-Anaerobic Energy Balance Compensation Theory

We recently reported that the restoration of cervical vertebral arterial blood flow access (measured as systolic peak (PS)) to the rhomboid fossa leads to the recovery of the HbA1c level in the case of patients with a pre-Diabetes Mellitus (pre-DM) condition. The theory of centralized aerobic-anaerobic energy balance compensation (TCAAEBC) provides a successful theoretical explanation for this observation. It considers the human body as a dissipative structure. Reported connections between arterial hypertension (AHT) and the level of HbA1c are linked through OABFRH. According to the TCAAEBC, this delivers incorrect information about blood oxygen availability to the cerebellum. The restoration of PS normalizes AHT in 5-6 weeks and HbA1c in 12-13 weeks. In the current study, we demonstrate the model which fits the obtained experimental data. According to the model, pathways of onset and recovery from pre-DM are different. The consequence of these differences is discussed. The great significance of the TCAAEBC for medical practice forces the creation of an appropriate mathematical model, but the required adjustment of the model needs experimental data which can only be obtained from an animal model(s). The essential part of this study is devoted to the analysis of the advantages and disadvantages of widely available common mammalian models for TCAAEBC cases.

Using Bayes theorem to estimate positive and negative predictive values for continuously and ordinally scaled diagnostic tests

OBJECTIVES

Positive predictive values (PPVs) and negative predictive values (NPVs) are frequently reported to put estimates of accuracy of a diagnostic test in clinical context and to obtain risk estimates for a given patient taking into account baseline prevalence in the population. In order to calculate PPV and NPV, tests with ordinally or continuously scaled results are commonly dichotomized at the expense of a loss of information.

METHODS

Extending the rationale for the calculation of PPV and NPV, Bayesian theorem is used to calculate the probability of disease given the outcome of a continuously or ordinally scaled test. Probabilities of test results conditional on disease status are modeled in a Bayesian framework and subsequently transformed to probabilities of disease status conditional on test result.

RESULTS

Using publicly available data, probability of a clinical depression diagnosis given PROMIS Depression scores was estimated. Comparison with PPV and NPV based on dichotomized scores shows that a more fine-grained interpretation of test scores is possible.

CONCLUSIONS

The proposed method bears the chance to facilitate accurate and meaningful interpretation of test results in clinical settings by avoiding unnecessary dichotomization of test scores.

HbA1c for screening and diagnosis of diabetes mellitus

HbA1c has become the gold standard for monitoring glycemic control in patients with diabetes mellitus. The use of this test has been expanded to diagnose and screen for diabetes mellitus with the endorsement of influential diabetes societies and the World Health Organization. The literature on the use of HbA1c for the diagnosis and screening of diabetes mellitus was critically examined. There is substantial recent literature on this topic with strong advocates for the use of HbA1c to diagnose and screen for diabetes and equally strong detractors for its use. Advocates of the use of HbA1c cite challenges in respect of patient compliance and the analysis of glucose and inconsistency of diagnosis with glucose-based diabetes diagnosis with the elimination or reduction in these challenges in HbA1c-based diagnosis. Detractors of its use cite increased cost, concerns about the availability of HbA1c testing, and the influence of demographic and clinical factors on HbA1c results that make the use of a single-threshold values questionable for different ethnic and age groups. Despite the recommendation of many international diabetes societies that HbA1c be used for screening and diagnosis of diabetes mellitus, there is a wide divergence of opinion on this use.