The full text of the original document is here and a concise summary was recently posted here at the Clinical Correlations blog.
The less aggressive BP targets recommended by JNC 8 represent a major shift in the approach to treatment of hypertension. I wonder if they'll change practice all that much, though, because hypertension tends to be under treated and uncontrolled BP levels in hypertension are widely ignored. Traditional thinking about hypertension has been that, down to some theoretical point where autoregulation fails and the patient experiences light headedness or other symptoms, the lower the BP is, the better. The new guidelines don't challenge the physiologic basis for that thinking but acknowledge that lower BP targets are not supported by high level evidence. The authors sought to be more strictly evidence based than JNC 7, relying solely on RCTs. (In the field of hypertension there have been a lot of them). The guideline did not draw on any meta-analyses or systematic reviews. The guideline authors did their own. So the paper is actually a guideline and a systematic review all in one document.