^#: a study can be awarded a maximum of one star for each numbered item within the “selection” and “outcome” category and a maximum of two stars can be given for “comparability”. For the “selection” category a star is awarded if the exposed cohort is representative; if the unexposed cohort is drawn from the same community as the exposed cohort; if exposure was ascertained by secure record or by a structured interview; and if it was demonstrated that outcome of interest was not present at the start of the study. For “comparability”, one star is awarded if the study controls for the most important factor and another star can be awarded if the study controls for any additional factor. For “outcome” a star is awarded if the assessment of the outcome is an independent blind assessment or by record linkage; if there was a long enough follow-up for the outcomes to occur; and if there was complete follow-up or if the fact that subjects were lost to follow-up is unlikely to introduce bias. ^¶: no comparison was made between individuals receiving appropriate treatment and inappropriate treatment since this was not the interest of the authors.