Mobile phone‐based interventions for improving adherence to medication prescribed for the primary prevention of cardiovascular disease in adults New


Abstract Background

Cardiovascular disease (CVD) is a major cause of disability and mortality globally. Premature fatal and non‐fatal CVD is considered to be largely preventable through the control of risk factors via lifestyle modifications and preventive medication. Lipid‐lowering and antihypertensive drug therapies for primary prevention are cost‐effective in reducing CVD morbidity and mortality among high‐risk people and are recommended by international guidelines. However, adherence to medication prescribed for the prevention of CVD can be poor. Approximately 9% of CVD cases in the EU are attributed to poor adherence to vascular medications. Low‐cost, scalable interventions to improve adherence to medications for the primary prevention of CVD have potential to reduce morbidity, mortality and healthcare costs associated with CVD.


To establish the effectiveness of interventions delivered by mobile phone to improve adherence to medication prescribed for the primary prevention of CVD in adults.

Search methods

We searched CENTRAL, MEDLINE, Embase, and two other databases on 21 June 2017 and two clinical trial registries on 14 July 2017. We searched reference lists of relevant papers. We applied no language or date restrictions.

Selection criteria

We included randomised controlled trials investigating interventions delivered wholly or partly by mobile phones to improve adherence to cardiovascular medications prescribed for the primary prevention of CVD. We only included trials with a minimum of one‐year follow‐up in order that the outcome measures related to longer‐term, sustained medication adherence behaviours and outcomes. Eligible comparators were usual care or control groups receiving no mobile phone‐delivered component of the intervention.

Data collection and analysis

We used standard methodological procedures recommended by Cochrane. We contacted study authors for disaggregated data when trials included a subset of eligible participants.

Main results

We included four trials with 2429 randomised participants. Participants were recruited from community‐based primary care or outpatient clinics in high‐income (Canada, Spain) and upper‐ to middle‐income countries (South Africa, China). The interventions received varied widely; one trial evaluated an intervention focused on blood pressure medication adherence delivered solely through short messaging service (SMS), and one intervention involved blood pressure monitoring combined with feedback delivered via smartphone. Two trials involved interventions which targeted a combination of lifestyle modifications, alongside CVD medication adherence, one of which was delivered through text messages, written information pamphlets and self‐completion cards for participants, and the other through a multi‐component intervention comprising of text messages, a computerised CVD risk evaluation and face‐to‐face counselling. Due to heterogeneity in the nature and delivery of the interventions, we did not conduct a meta‐analysis, and therefore reported results narratively.

We judged the body of evidence for the effect of mobile phone‐based interventions on objective outcomes (blood pressure and cholesterol) of low quality due to all included trials being at high risk of bias, and inconsistency in outcome effects. Of two trials targeting medication adherence alongside other lifestyle modifications, one reported a small beneficial intervention effect in reducing low‐density lipoprotein cholesterol (mean difference (MD) –9.2 mg/dL, 95% confidence interval (CI) –17.70 to –0.70; 304 participants), and the other found no benefit (MD 0.77 mg/dL, 95% CI –4.64 to 6.18; 589 participants). One trial (1372 participants) of a text messaging‐based intervention targeting adherence showed a small reduction in systolic blood pressure (SBP) for the intervention arm which delivered information‐only text messages (MD –2.2 mmHg, 95% CI –4.4 to –0.04), but uncertain evidence of benefit for the second intervention arm that provided additional interactivity (MD –1.6 mmHg, 95% CI –3.7 to 0.5). One study examined the effect of blood pressure monitoring combined with smartphone messaging, and reported moderate intervention benefits on SBP and diastolic blood pressure (DBP) (SBP: MD –7.10 mmHg, 95% CI –11.61 to –2.59; DBP: –3.90 mmHg, 95% CI –6.45 to –1.35; 105 participants). There was mixed evidence from trials targeting medication adherence alongside lifestyle advice using multi‐component interventions. One trial found large benefits for SBP and DBP (SBP: MD –12.45 mmHg, 95% CI –15.02 to –9.88; DBP: MD –12.23 mmHg, 95% CI –14.03 to –10.43; 589 participants), whereas the other trial demonstrated no beneficial effects on SBP or DBP (SBP: MD 0.83 mmHg, 95% CI –2.67 to 4.33; DBP: MD 1.64 mmHg, 95% CI –0.55 to 3.83; 304 participants).

Two trials reported on adverse events and provided low‐quality evidence that the interventions did not cause harm. One study provided low‐quality evidence that there was no intervention effect on reported satisfaction with treatment.

Two trials were conducted in high‐income countries, and two in upper‐ to middle‐income countries. The interventions evaluated employed between three and 16 behaviour change techniques according to coding using Michie's taxonomic method. Two trials evaluated interventions that involved potential users in their development.

Authors' conclusions

There is low‐quality evidence relating to the effects of mobile phone‐delivered interventions to increase adherence to medication prescribed for the primary prevention of CVD; some trials reported small benefits while others found no effect. There is low‐quality evidence that these interventions do not result in harm. On the basis of this review, there is currently uncertainty around the effectiveness of these interventions. We identified six ongoing trials being conducted in a range of contexts including low‐income settings with potential to generate more precise estimates of the effect of primary prevention medication adherence interventions delivered by mobile phone.


Melissa J Palmer, Sharmani Barnard, Pablo Perel, Caroline Free


Plain language summary

Interventions delivered by mobile phone to help people adhere to medication to prevent cardiovascular disease 

Review question 

We reviewed the evidence on the effect of interventions delivered by mobile phone to help people in taking their medication to prevent cardiovascular disease (for example, heart attacks and strokes). We found four studies which included 2429 participants.


Around 17.6 million people die from cardiovascular disease every year. Medications can help to prevent cardiovascular disease; however, many people who have been given these medications do not take them as often or as consistently as recommended. This means that the medication will not work as well as it could to prevent cardiovascular disease. Interventions delivered through mobile phones, for example, prompting by text messaging, may be a low cost way to help people to take their medication as recommended.

Study characteristics 

The evidence is up to date to June 2017. We found four studies that tested interventions delivered at least partly by mobile phone, which followed up participants for at least 12 months.

Key results 

We were not able to combine the results of the four trials because the interventions were very different. The studies were at high risk of bias and the effects of the interventions were inconsistent across studies, and so, we are not confident about their findings. The evidence suggests that interventions delivered by mobile phone may help people to take their medication, but the benefits are small, and some trials found that the interventions did not have any beneficial effect. There was no evidence to suggest that these types of interventions caused harm. The results of trials currently being conducted should tell us the effects of these types of interventions more accurately, and will tell us if they work in a wider range of contexts, including low‐income countries.


Melissa J Palmer, Sharmani Barnard, Pablo Perel, Caroline Free

Reviewer's Conclusions

Authors' conclusions

Implications for practice

Our results are based on four trials, none of which was considered to be at low risk of bias. Therefore, given the low quality of the evidence presented, the implications for practice are limited. From the four studies reporting on change in systolic blood pressure as an outcome, effects ranged from reductions of 12.5 mmHg to increases of 0.83 mmHg, with two studies exceeding a 5 mmHg mean reduction (a 5 mmHg reduction in systolic blood pressure is generally considered to result in clinically important reductions in the relative risk of stroke and coronary heart disease events (Collins 1990)). The delivery of mobile phone‐based interventions is inexpensive and previous analyses of such interventions in other fields have demonstrated cost‐effectiveness (Guerriero 2013; Lester 2010). If comparable effectiveness results are replicated in other high‐quality trials, it would be useful to consider cost‐effectiveness of the intervention, as if shown to be cost‐effective, the small benefits achieved at low cost might be important if achieved across whole populations. The Cholesterol Treatment Trialists' Collaboration estimates that for each 1 mmol/L (38.67 mg/dL) reduction in low‐density lipoprotein cholesterol (LDL‐C) there is a consistent 20% relative risk reduction for major vascular events regardless of baseline risk (CTT 2012). The two trials measuring LDL‐C as an outcome reported effects ranging from a 9.2 mg/dL reduction to a 0.77 mg/dL increase, meaning that even the larger of these effects would have a small impact on clinical outcomes.

Implications for research

The intervention delivered by SMS alone which resulted in small benefits in adherence was developed with input from users. The intervention targeted many of the barriers to adherence, which might conceivably be addressed using SMS, employing a wide range of behavioural change techniques. Nonetheless, the finding of only small benefit is consistent with results of adherence interventions delivered by SMS for secondary prevention of CVD, HIV medication and diabetes (Adler 2017; Anglada‐Martinez 2015; Farmer 2016). It is possible that the intervention delivered by SMS has small effects because some behaviour change techniques may not be effective when adapted for delivery by SMS. Adherence is influenced by a wide range of service and social factors, in additional to the individual level factors like knowledge motivation and skills which might be targeted using short written messages (DiMatteo 2004; Julius 2009; Kardas 2013; Nieuwlaat 2014; Pound 2005; Vermeire 2001). Future adherence interventions should consider targeting a broader range of factors influencing adherence. Given the importance of healthcare providers in influencing medication use and altering medication if unacceptable adverse effects occur, interventions may require integration with services to result in clinically important benefits for individuals. Furthermore, future trials should consider targeting people most at risk of poor adherence and excluding those known to be adherent.

Finally, given the heterogeneity that exists between behaviour change interventions, we believe there is a case to be made that individual high‐quality adequately powered trials could provide higher quality evidence relating to the effectiveness of such interventions, compared with evidence based on attempts to pool multiple smaller, lower‐quality and potentially heterogeneous trials. Several of the ongoing trials identified have large sample sizes, and so if adequately powered and at low risk of bias, these studies may provide high‐quality and more precise estimates of the effect of adherence interventions delivered by mobile phone.

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