Methodological quality assessment based on the NOS.^a

Abstract

a<p>Assessed with the 9-star Newcastle-Ottawa Scale(NOS).</p>b<p>Adequate definition of cases(0,1star).</p>c<p>Consecutive or obviously representative series of cases (0,1).</p>d<p>Selection of controls: Community controls (0,1).</p>e<p>Definition of controls: No history of disease (endpoint) (0,1).</p>f<p>Study controls for the most important factor or any additional factor(0,1,2).</p>g<p>Secure record (eg surgical records) (0,1).</p>h<p>Same method of ascertainment for cases and controls(0,1).</p>i<p>Same non-response rate for both groups(0,1).</p>j<p>Total: minimum equals 1; maximum equals 9 stars.</p