Table 2 Quality assessment grading as described by Downe, Simpson and Trafford [55]

A—No or few flaws

High credibility, transferability, dependability and confirmability

B—Some flaws

Unlikely to affect the credibility, transferability, dependability and/or confirmability of the study

C—Some flaws

May affect the credibility, transferability, dependability and/or confirmability of the study

D – Significant flaws

Very likely to affect the credibility, transferability, dependability and/or confirmability of the study