Comparison of adherence measures using claims data in the South African private health sector.

BACKGROUND: Medication adherence measurement is becoming increasingly important. Biological assays and markers, directly observed therapy, self-reports, pill counts and surveys have been successfully used to assess adherence under various circumstances, but may be limited by cost, ethical concerns and self-reported bias. Administrative claims data, in addition to offering a solution to these limitations, provide access to large study populations under real clinical practice situations, and in a timely and effective manner. With the wide range of adherence measures determined from claims data available - some of which have been found to be mathematically equivalent - researchers are often faced with the decision of choosing which is appropriate. An assessment of the various measures is therefore important for better understanding and to facilitate future adherence studies using administrative data. OBJECTIVES: To compare different adherence measures using data from a medicines claims database in South Africa (SA), employing montelukast for the purpose of illustration. METHODS: This retrospective, cross-sectional research used data from 1 January 2006 to 31 December 2015 from a privately owned pharmaceutical benefits management (PBM) company in SA. Claims for montelukast were identified and adherence was determined using the continuous multiple-interval measure of oversupply (CMOS), compliance ratio (CR), modified medication possession ratio (MPRm), refill compliance rate (RCR), continuous single-interval measure of medication acquisition (CSA) and proportion of days covered (PDC) capped at 1. The measures were compared with the medication possession ratio (MPR) as the reference. RESULTS: The MPR, CMOS and CR were equivalent, each yielding an adherence value of 86%. The MPRm, RCR and average CSA yielded higher adherence values of 96.9%, 117.2% and 129.0%, respectively, whereas the PDC produced a lower adherence value of 76.0%. The measures that used the entire study period as the denominator produced consistent results compared with the measures that used the difference between claims dates as denominator. CONCLUSIONS: The MPR is considered the most widely used metric to measure adherence using administrative data, but it may not always be applicable owing to the type of data available. Adherence computed using the CR, CMOS and PDC capped was found to be comparable to the MPR, and they may therefore be used as alternatives.

Associations between dietary salt, potassium and blood pressure in South African adults: WHO SAGE Wave 2 Salt & Tobacco.

BACKGROUND & AIMS: In June 2016, South Africa implemented legislation mandating maximum sodium levels in a range of processed foods with a goal of reducing population salt intake and disease burden from hypertension. Our aim was to explore the relationship between salt and blood pressure (BP) in a subsample of the World Health Organization Study on global AGEing and adult health (SAGE) Wave 2 before implementation of legislation in South Africa. METHODS & RESULTS: Blood pressure (BP) was measured in triplicate (n = 2722; median age 56 years; 33% male) and 24-h urine collected in a nested subsample (n = 526) for sodium, potassium and creatinine analysis. Hypertension prevalence was 55% in older adults (50-plus years) and 28% in younger adults (18-49 years). Median salt intake (6.8 g/day) was higher in younger than older adults (8.6 g vs 6.1 g/day; p < 0.001), and in urban compared to rural populations (7.0 g vs 6.0 g/day; p = 0.033). Overall, 69% of participants had salt intakes above 5 g/day. Potassium intakes were generally low (median 35 mmol/day) with significantly lower intakes in rural areas and older adults. Overall, 91% of adults failed to meet the daily potassium recommendation of 90 mmol/d. Salt intakes above 5 g/day, and to a greater extent, a dietary sodium-to-potassium (Na:K) ratio above 2 mmol/mmol, were associated with significantly steeper regression slopes of BP with age. CONCLUSION: These preliminary results indicate that high dietary Na:K ratio may lead to a greater increase in BP and hypertension risk with age. Interventions to increase potassium intakes alongside sodium reduction initiatives may be warranted.

The association between seven-day objectively measured habitual physical activity and 24 h ambulatory blood pressure: the SABPA study.

Few studies have examined objective physical activity in relation to 24 h ambulatory blood pressure (BP). We aimed to assess the association of 7-day objectively measured habitual physical activity with ambulatory BP in a sample of African and Caucasian school teachers (n=216, age 49.7 years) from the sympathetic activity and blood pressure in Africans prospective cohort study. Hypertension (ambulatory systolic BP⩾130 and/or diastolic BP⩾80 mm Hg) was prevalent in 53.2% of the sample, particularly in black Africans. The hypertensive group spent significantly more awake time in sedentary activity (51.5% vs 40.8% of waking hours, P=0.001), as well as doing less light- (34.1% vs 38.9%, P=0.043) and moderate-intensity (14.0% vs 19.7%, P=0.032) activities compared with normotensives, respectively. In covariate adjusted models, light-intensity activity time was associated with lower 24 h and daytime ambulatory systolic BP (ß=-0.15, 95% confidence interval (CI): -0.26, -0.05, P=0.004; ß=-0.14, CI: -0.24, -0.03, P=0.011) and diastolic BP (ß=-0.14, CI: -0.25, -0.03, P=0.015; ß=-0.13, CI: -0.24, -0.01, P=0.030), as well as resting systolic BP (ß=-0.13, CI: -0.24, -0.01, P=0.028). Sedentary time was associated only with 24 h systolic BP (ß=0.12; CI: 0.01, 0.22), which was largely driven by night-time recordings. Participants in the upper sedentary tertile were more likely to be 'non-dippers' (odds ratio=2.11, 95% CI: 0.99, 4.46, P=0.052) compared with the lowest sedentary tertile. There were no associations between moderate to vigorous activity and BP. In conclusion, objectively assessed daily light physical activity was associated with ambulatory BP in a mixed ethnic sample.