Thirdly, patients who drop out because of drug-related side effects or non- adherence are usually accounted for in intention-to-treat analyses and the overall proportion of dropouts is not often reported (although may be 10% or more of the recruited population). Finally, although the mean achieved BP is often close to the intended target, the SD of the reported BP measurements is often large, suggesting that the recorded values in many patients are well above the mean and hence well above the target.22 Only rarely is the actual number of patients not achieving the target BP reported. Taken together, these factors indicate that the proportion of patients with CKD in whom BP cannot be controlled to a specified target may be much higher than indicated by the data derived from RCTs. Patients do not adhere to the treatment. The reasons why patients do or do not adhere to medical advice are believed to depend in part on cost benefit analysis by the patients themselves. This is particularly relevant to the use of BP- modifying drugs that do not provide immediately perceivable improvement in quality of life or relief of symptoms, yet have immediately observable negative effects in terms of expense and inconvenience, even if there are no adverse side effects. The literature contains many reports of poor adherence to BP-modifying drug regimens and suboptimal BP control in CKD patients is known to be associated with poor adherence BP fluctuates. In a usual clinical setting, if a BP target is set, a clinician will gradually increase the number of drugs prescribed to a given patient until this target is achieved. The regimen will not then be altered again unless several BP readings are above (sometimes well above) that target. 