Table 1.

Assessment of observing study quality based on the standard recommended by AHRQ

Assessing principala
Study question clearly focused
Sampling of Study Population (Random, Convenient, Self-selected)
Clear definition of including or excluding criteria
Clear definition of research time
Assessment of confounding effects of various factors (for example, age of the patients, patient sex)
Appropriate measure of precision
Clear description of response rate
Clear description of dealing with missing data
Conclusions supported by results with possible bias and limitations taken into consideration

^ascoring method: yes = 1; no or not mentioned = 0