The study used a customised risk calculator to stratify participants into risk groups. It was unclear how risk was calculated and whether the groups were similar to validated risk tools such as Framingham, QRISK2 or 3. The risk calculator also used previous cardiovascular events, which is not considered a useful measure and is not included in any validated risk tools.

The cardiovascular risk groups compared within each category also differed within each outcome, which made results difficult to interpret.

The population didn’t match this review protocol’s requirements: unclear if participants were already treated or on other treatment (55.9% had previous treatment) and unclear if baseline cardiovascular risk was measured while participants were untreated. 39.1% of the population had diabetes with no detail of whether this was type 1 or type 2 diabetes.

Pooled trial data of ‘less intensive arms’ with placebo, which was an exclusion criterion on the protocol for this review.

No minimum trial duration inclusion criterion, whereas this review had a requirement of trials with a minimum duration of 12 months.

The trialists used meta-regression with the observed 5-year risks to extend all results to 5 years; the average follow up time was not stated.

For the blood pressure categories outlined in the protocol for this review, the only available outcome was major cardiovascular events. This composite outcome was included in the review protocol but was only to be included if individual cardiovascular event outcomes were not available. This is because these outcomes were considered to be more informative.

Individual morbidity and mortality outcomes were given at systolic blood pressure thresholds of above 140 mmHg and below 140 mmHg. Above 140 mmHg was not a threshold listed in the protocol and would not have informed recommendations as this encompasses stage 1 and stage 2 hypertension. The below 140 mmHg comparison was considered for inclusion but 58.9% had other cardiovascular disease and were taking medication for secondary prevention.

Baseline characteristics were not stated, and the IPD included participants that were already treated; it was unclear if baseline blood pressure had been measured while participants were untreated.

Study carried out in Japan and considered not to be applicable to the UK population due to the known differences in antihypertensive treatment and prevalence of cardiovascular events, that is, different antihypertensive drugs administered and lower dosages of treatment given than in the UK. The prevalence of stroke and heart failure are higher in Japan, which were the only included outcomes in the IPD. In addition, the incidence of myocardial infarction tends to be lower in Japanese people with hypertension, which is an outcome of interest for this guideline.

The comparisons included were not in line with this review protocol. Rather than comparing treatment versus no treatment at each blood pressure threshold, the IPD compared treatment at each threshold versus no treatment in the ‘optimal’ below 120 mmHg systolic blood pressure category. This would have substantially influenced the results.

Unclear from the IPD whether baseline blood pressure was measured before treatment was initiated.

There is an overlap in included studies included in this review with those included in Sundstrom 2015.¹⁶² The IPD (Sundstrom) was therefore preferentially included.

There is an overlap in included studies included in this review with those included in Sundstrom 2015.¹⁶² The IPD (Sundstrom) was therefore preferentially included.

Stratified by above 140 mmHg and below 140 mmHg; above 140 mmHg was not a threshold listed in the protocol and would not have informed recommendations as this encompasses stage 1 and stage 2 hypertension. 65% of the population in the below 140 mmHg threshold had other cardiovascular disease and were taking antihypertensive medication for secondary prevention

Majority of participants had coronary heart disease and 15–40% had heart failure, which were not included in this review.