Herpes simplex virus type-1 (HSV-1), another alpha-herpesvirus, had its gene expression and replication regulated by thyroid hormone (TH) using molecular biology techniques.
Due to the homology of HSV-1 and VZV, the researchers theorised that people who have had a history of TH imbalance or dysfunction may have a higher risk of VZV reactivation.
The researchers used a retrospective case-control design to establish if the link between TH imbalance and the VZV was present.
The researchers first set up an Inclusion and Exclusion criteria, where conditions for inclusion were hypothyrodism (TH) and positive VZV-zoster diagnoses which corresponded to ICD-9-CM codes of 244.0-244.9, and 053.0-053.9, respectively.
They then identified subpopulations of interest and excluded patients with other disorders that might induce variables into the study.
This study encompasses three phases of statistical evaluations, where:
The first stage compares the chances of VZV-zoster diagnosis/reactivation in both the TH positive and TH negative patients by 2×2 contingency table analyses and also evaluated the risk, risk ratio, odds, and odds ratio (OR).
An OR >1 is significant in demonstrating the suspected effects of TH, and a much greater OR would considerably strengthen the hypothesis as the variables are kept constant.
The second stage was designed to show the correlation between the VZV-zoster and TH groups. Hence , a experimental hypothesis stating that the groups are related was formulated with the null hypothesis claiming otherwise. The relations between groups was tested using a Chi-square (χ2) test of independence.
Values of χ2 > p-value of 0.05 would be considered significant, and the null hypothesis would be rejected, proving that the VZV and TH groups are related.
The third stage aimed to confirm the theory that the VZV patients, as identified using the ICD-9 code 053, were suffering VZV reactivation and not primary chickenpox (CKP) infection (ICD-9 code 052). To do so, both OR and χ2 were calculated. The chances of VZV-varicella diagnosis in both the TH positive and TH negative patients were used as a control.
“ Further analyses indicated that African American males exhibited a much higher chance of simultaneous diagnoses. These results show that a TH imbalance history may affect VZV reactivation at different incidence rates in different races and age groups.”