DIGIHLTH 706 Assignment 2

SECTION A

Refer to the paper Post-licensure zoster vaccine effectiveness against herpes zoster and postherpetic neuralgia in older adults: A systematic review and meta-analysis. (Mbinta et al, 2022). This can be accessed via Canvas Reading Lists

The virus that causes chicken pox (varicella) is called varicella-zoster. The virus can sit dormant in the body for years until something triggers it to reactivate in adulthood and cause shingles (herpes zoster).  There are vaccines to prevent the onset and/or reduce the severity of the complications of shingles and this study looks at how well they work.

Many websites will give you more info about shingles and one I’d recommend is the Centre for Disease Control.

Question 1 (2 pts)

In the paper by Mbinta et al, how many studies were included in the final systematic review and how many were in the meta-analysis, and why is there a difference?

Question 2 (1 pts)

Why did this study about vaccine effectiveness include literature from study designs other than randomised controlled trials?

Question 3 (2 pts)

What intervention and comparison needed to be reported in a study for it to be included in the systematic review?

Question 4 (1 pts)

The methodological quality of eligible studies was critically appraised by two independent reviewers using the Joanna Briggs Institute criteria. What were the findings of that evaluation?

Question 5 (0.5pts)

What effect of interest was extracted from eligible studies?

Question 6 (1 pts)

Why was an odds ratio not selected as the effect of interest?

The following four questions (Qu 7-10) relate to the meta-analysis of vaccine effectiveness of ZVL against herpes zoster in immunocompromised adults.

Question 7 (1 pts)

How many studies were in the meta-analysis of vaccine effectiveness of ZVL against herpes zoster in immunocompromised adults?

Question 8 (0.5 pts)

Did the 95% confidence intervals of those studies overlap?

Question 9 (1 pts)

What was the lower age limit in the study that contributed the least weight to this analysis of immunocompromised adults?

Question 10 (1 pts)

What was the proportion of dispersion across studies due to true heterogeneity rather than sampling error in that comparison?

Question 11 (1 pts)

A key result from the meta-analysis is that “The overall pooled vaccine effectiveness of ZVL against herpes zoster was 45.9% (95% CI 42.2-49.4)”.  What is the hazard ratio and 95% confidence interval that this result is derived from, reported to 2 decimal places?

Question 12 (3 pts)

Did ZVL vaccine effectiveness wane over time? Provide results to support your answer.

SECTION B

You are reading a report about a national cancer registry of 29,998 people who had received surgery for a type of cancer between the years 1990 and 2000.

Figure 1 (shown below) is from a time-to-event analysis of cancer recurrence, stratified by the size of the tumour that had been removed during the initial surgery.

T1 (red line) = tumour diameter was at least 15 mm, T2 (orange line) = tumour diameter was 5-14 mm, T3 (blue line) = tumour diameter was <5mm. The shading around each line represents the 95% confidence interval.

Please note that this question uses fictitious data.  The scenario is based on real data but the comparisons and findings are not real.

Question 13 (1 pts)

What number and % of the 29,998 people who received surgery are in the analysis shown in Figure 1?

Question 14 (1.5 pts)

Give 3 reasons why fewer people are in this analysis than had surgery.

Question 15 (0.5 pts)

What percentage of people with a tumour diameter of 5-14 mm who were at risk at 15 years since surgery were still at risk at 25 years?

Question 16 (3 pts)

Interpret the analysis based on the information provided. Include an estimation of the relative risk of recurrence at the end of reported follow-up for people who had a tumour at least 15 mm in diameter compared to people who had a tumour diameter of <5mm.

Write no more than one paragraph in total.

Question 17 (1 pts)

Registry data on surgeries performed for this type of cancer in 1979 to 1989 had shown that the risk of cancer recurrence within 25 years was significantly higher for people aged < 45 years than it was for people aged 45 years or older, reported as a hazard ratio (HR) of 1.24 (95% confidence interval 1.19 to 1.29).

The analysis was repeated in this current report for surgeries performed between 1990 and 2000. The result was a HR of 1.08 (95% confidence interval 0.98 to 1.18).  Interpret this latest result.