Jalkanen 1991.

Methods	DESIGN: parallel, randomised, no information on blinding DURATION: 12 months NUMBER OF STUDY CENTRES: 2 COUNTRY OF PUBLICATION: ‐ SPONSOR: ‐
Participants	WHO PARTICIPATED: overweight hypertensive patients (selected from files) SETTING: outpatient clinic (2 hypertension clinics in Finland) MAIN INCLUSION CRITERIA: age 35 to 59 years; BMI 27 to 34 kg/m2; DBP ≥ 95 mm Hg MAIN EXCLUSION CRITERIA: ‐ NUMBER: 25 vs 25 were randomised; 24 vs 25 were analysed (dietary intervention vs no dietary intervention) GENERAL BASELINE CHARACTERISTICS (dietary intervention vs no dietary intervention): MEAN AGE [YEARS]: 49 GENDER [% MALE]: ‐ (" ... as many men as women ... ") NATIONALITY: ‐ ETHNICITY: ‐ WEIGHT [kg]: 86 vs 80 BODY MASS INDEX [kg/m2]: ‐ SYSTOLIC BLOOD PRESSURE [mm Hg]: 152 vs 155  DIASTOLIC BLOOD PRESSURE [mm Hg]: 101 vs 102  COMORBID CONDITIONS: ‐ ANTIHYPERTENSIVE TREATMENT: ‐ (25 of 50 enrolled participants antihypertensive treatment with diuretics or ß‐blocker) DURATION OF HYPERTENSION: ‐ SUBGROUP ANALYSES: ‐
Interventions	LENGTH OF FOLLOW‐UP: 12 months DIETARY INTERVENTION: individually planned energy‐restricted diet of 1000 to 1500 kcal per day, weekly (after 6 months every 3 weeks); sessions including discussions and lessons on behavioural modification, choice of food, physical exercise, and medical aspects of overweight and weight reduction; 1.5 hour duration; total number of lectures about 40 hours; the participants received leaflets on the reduction of salt and fat consumption and on the increase of physical activity; lectures by different medical experts; nutritionists interview; laboratory tests NO DIETARY INTERVENTION: visits every 3 months; no personal counselling; nutritionists interview; laboratory tests ADDITIONAL TREATMENT: participants' doctors were asked to keep the dosage of antihypertensive drugs at the initial level
Outcomes	PRIMARY OUTCOMES: 1. MORTALITY: ‐ 2. CARDIOVASCULAR MORBIDITY: ‐ 3. ADVERSE EVENTS: ‐ SECONDARY OUTCOMES: 1. CHANGES IN SYSTOLIC BLOOD PRESSURE [mm Hg]: Definition: SBP change from baseline to endpoint visit 2. CHANGES IN DIASTOLIC BLOOD PRESSURE [mm Hg]: Definition: DBP change from baseline to endpoint visit 3. BODY WEIGHT [kg]: Definition: body weight change from baseline to endpoint visit ADDITIONAL OUTCOMES MEASURED IN THE STUDY: 1. Change in lipid parameters 2. Change in potassium and sodium excretions 3. Change in dietary factors (fats and protein)
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: No details on generation sequence are provided
Allocation concealment (selection bias)	Unclear risk	Comment: Method of concealment is not described
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Comments: No description of randomisation; no information on blinding for investigators
Incomplete outcome data (attrition bias) All outcomes	High risk	WITHDRAWALS (dietary intervention vs no dietary intervention): 1 vs 0 REASONS/DESCRIPTIONS: ‐
Selective reporting (reporting bias)	Unclear risk	Comment: No primary and secondary outcomes were defined
Other bias	High risk	Comments: 1. Lack of information on randomisation and concealment of allocation and blinding increases risk of bias 2. No information provided on the reason for and description of the dropout in the intervention group 3. The effect of weight reduction is not clearly identified; advice about behavioural modification, physical exercise, and salt reduction were also part of the intervention