Background
Anaemia is a condition in which the oxygen-carrying capacity of the blood is insufficient to meet the physiologic needs of body tissues. Approximately 29% of the nonpregnant women internationally experience this condition. Multiple direct causes of anaemia that frequently exist are: parasitic infections; inflammatory disorders; inherited disorders of haemoglobin (Hb) structure; and vitamin and mineral deficiencies such as that of vitamins A and B12, and folate, and the most prevalent, iron. Worldwide figures suggest that 50% of anaemia is attributable to iron deficiency. Iron deficiency may derive from inadequate dietary iron intake, poor iron absorption or utilization, increased iron requirements, or blood loss - acute or chronic. The WHO1 recommends daily oral iron for pregnant women to prevent maternal anaemia, puerperal sepsis, low birth weight, and preterm birth, and folic acid to prevent neural tube defects, usually supplemented together.
Iron deficiency anaemia may cause impaired muscle function and reduced resistance to infections, and is associated with reduced physical capacity and work performance in adolescents and adults. Conventionally, daily iron supplementation has been a standard practice for preventing and treating anaemia. Nevertheless, it has been associated with adverse side effects such as gastrointestinal disturbances, including nausea, constipation, diarrhoea, and teeth staining, which may lead to issues with compliance. The administration of intermittent iron supplementation - where supplements are administered once or twice a week on nonconsecutive days alone or with any other vitamins and minerals - is recommended as an effective and more tolerable alternative to prevent and reduce the incidence of anaemia and may in effect increase compliance. Improving iron and folate nutrition of adolescent and adult menstruating women may enhance maternal and infant health outcomes considerably.
Objective/s
The objectives for this review were to
1. assess the effects of intermittent oral iron supplementation, alone or in combination with other nutrients, on anaemia; and
2. assess the associated deficiencies among menstruating women, compared with no intervention, a placebo, or daily supplementation.
Intervention/Methods
The current review considered both randomized and quasirandomized controlled trials (RCTs), which compared either intermittent iron supplementation (alone or with any other micronutrients) versus no supplementation or placebo, or intermittent iron supplementation versus daily iron supplementation.2
The participants of interest were menstruating women, who were not pregnant or lactating and did not have a known condition that impeded the presence of menstrual periods and prior to the menopause, regardless of their baseline iron status or anaemia status, ethnicity, or country of residence.
The search strategy (conducted in February 2018) was comprehensive and included multiple electronic databases and clinical trial registries, which included a review on inclusion criteria, trial quality, and extracted data. The quality of the evidence was assessed using the GRADE approach,3 to appraise evidence for clinically relevant outcomes. Data collected were analysed as per the established methods of the Cochrane Collaboration.
Results
The evidence from 25 RCTs, involving 10 996 participants in low-to-middle-income countries, consistently demonstrated that intermittent iron supplementation compared with no intervention or a placebo, reduced the risk of having anaemia. A meta-analysis on four studies proposed that women receiving iron supplements daily had higher concentrations of ferritin, though the results were inconclusive and should be interpreted with caution, as there was substantial heterogeneity between studies in these analyses. There was little evidence available of the effect of iron supplementation on iron deficiency anaemia and associated morbidity such as side effects (such as nausea, constipation, and teeth staining), work performance and economic productivity, depression, and adherence to the intervention. The overall quality of evidence was defined as low-to-moderate quality, because of the lack of reported methodological details and reported data outcomes.
Conclusion
The current evidence suggests that the administration of intermittent iron supplementation compared with daily supplementation in menstruating women may be as effective at reducing anaemia and improving Hb concentrations. In addition, this treatment is associated with fewer side effects compared with daily supplementation. The quality of the evidence was on average low, meaning that the confidence in the outcome measures is limited, leading to uncertainty that these results show the true effect and they may change with additional data. There is a need for more high quality, and adequately powered, studies to assess the effects of iron supplementation regimes on all populations. More information is required on morbidity, side effects, work performance, economic productivity, and adherence to the intervention. Data about effects on long-term supplementation, later health and development, or effects in low-resource settings, are required.
Implications for practice
Intermittent iron supplementation in menstruating women may be an effective intervention for reducing anaemia and improving Hb concentrations. This regime may also be associated with fewer side effects compared with no treatment, placebo or daily supplementation. However, it is important to establish the most effective schedules for the treatment and prevention of anaemia in all populations, such as in low-income countries where parasitic infections are more common. Future research would provide much needed evidence in this area, and nurses and midwives are ideally positioned to lead, participate in and advocate for such research.
Acknowledgements
Conflicts of interest
The author reports no conflicts of interest.
* A member of Cochrane Nursing Care (CNC).
References