Although the burden of neonatal encephalopathy is far higher in low and middle-income countries, the safety and efficacy data on cooling therapy from high income cooling trials cannot be extrapolated to these settings.

Firstly, all high-income country clinical trials to date have provided cooling therapy along side optimal tertiary neonatal intensive care and cardiorespiratory support. Such tertiary care includes 1:1 expert nursing care, continuous clinical monitoring of vital physiological parameters, close attention to acid base and electrolyte balance, optimal ventilatory and inotropic support, parenteral nutrition, nitric oxide and cerebral function monitoring. These centres also have access to extra-corporeal membrane oxygenation (ECMO) facilities for infants with persistent pulmonary hypertension and meconium aspiration that may be adversely affected by cooling. The safety and efficacy of cooling therapy without optimal tertiary neonatal intensive care is unknown. Even the best resourced public sector tertiary neonatal units in India and other low and middle-income countries do not have the facilities and expertise that are comparable to the neonatal units where the high-income cooling trials were originally performed. The dangers of extrapolating the safety and efficacy data from high income country intensive care units to low and middle-income countries is well known, and has been recently re-emphasised by the increased mortality seen after fluid boluses in children with septic shock in Africa (FEAST trial). The HELIX trial will examine the safety of cooling therapy in under resourced public sector neonatal units in India, who do not have the above-mentioned facilities for providing optimal tertiary intensive care, alongside cooling therapy. Secondly, there are significant population differences in babies who suffer from encephalopathy in high-income countries and those in low and middle-income countries with a higher incidence of perinatal infection and meconium aspiration. Antenatal care is often poor, and intra uterine growth restriction and delayed hospital admission in obstructed labour are extremely common.

Thus the brain injury may be more chronic and already established, such that the window period for cooling may be already lost by the time baby is born. Two recent NICHD hypothermia workshops (2011 and 2013)14 involving experts in therapeutic hypothermia have recommended that rigorous evaluation of cooling therapy should be urgently conducted in LMIC, to ensure that the benefits of one of the most important discoveries in neonatal medicine are not lost to the population that needs it most. Without such rigorous evaluation there may be a creeping introduction of cooling therapy, which is constantly sabotaged by residual safety concerns, and it will never be widely used in India and other LMIC.

Cooling studies from low and middle-income countries A number of small randomised controlled trials have been reported from low and middle-income countries. Individual studies were small and of poor quality. The largest of these trials reported from China had excluded babies at risk of perinatal sepsis and had substantial methodological concerns. Two studies reported increased mortality with cooling. Meta-analysis of all these trials showed a trend towards reduced mortality, however this was not statistically significant (RR 0.74; 95% CI 0.4 to 1.3). More importantly, the confidence intervals were wide and therefore significant benefits or harm cannot be excluded. There were no data on long term neurological follow up after cooling therapy. In preparation for the HELIX trial, the investigators conducted a feasibility study of cooling therapy using a servo controlled cooling device (Tecotherm) in 2013/14, at Madras Medical College (MMC), Chennai. The data from 58 cooled babies with neonatal encephalopathy and 112 contemporary 'un matched' encephalopathic babies who had usual care (normothermia) admitted to the neonatal unit over a 15 month period are given below . Although the neonatal mortality in the cooled babies appears to be higher than the high-income country cooling trials, it was lower than the contemporary encephalopathic population at this hospital. High incidence of gastric bleeds and persistent metabolic acidosis were seen in both groups. The cases and controls were not matched and it is possible that the control babies were more unwell, and therefore had higher mortality (29% versus 54%; Table 1); nevertheless, these data are reassuring and support further evaluation of cooling therapy in a rigorous randomised controlled trial (manuscript in preparation). A paradox of private and public sector health care exists in India and other low and middleincome countries. Private hospitals are often very well equipped and have good tertiary intensive care facilities, but are not affordable to the low income populations. Moreover, these hospitals are relatively smaller (annual delivery rates of less than 2000), and have a low encephalopathy burden. Public sector hospitals on the other hand, tend to be much larger (20,000 to 30,000 deliveries per year) and offer free health care to the low income population. These hospitals have a huge encephalopathy burden (both inborn and out-born babies), but lack resources and good neonatal intensive care facilities. Thus, significant health benefits will occur only if the neuroprotective therapies are usable and indeed effective in public sector hospitals in the low and middle-income countries, rather than in private health care.

The HELIX trial is carefully designed to be generalizable to all under-resourced neonatal units with sub optimal neonatal intensive in India and other low and middle-income countries, that bear a very high neonatal encephalopathy burden. However, the neonatal units need to have a good quality basic neonatal care, including facilities of neonatal resuscitation, administration of intravenous fluids, drugs and basic respiratory support, but not optimal cardio respiratory or 1:1 nursing care facilities. The HELIX trial will be conducted in the real life situation of under resourced public sector neonatal units lacking optimal tertiary intensive care in India. Exclusively clinical criteria will be used for case identification and recruitment, and no laboratory parameters, neuroimaging or cerebral function monitoring will be required for eligibility. The entire cooling therapy will be provided by the existing clinical teams, and the research team will only be involved in accurate and high quality data collection, so that the trial results are reflective of the routine clinical scenario. Clearly, the population co-morbidities and resources in Indian neonatal units are different to African and other low-income country neonatal units. If the HELIX trial results suggest that cooling is safe and effective in Indian neonatal units, the next stage would be to evaluate cooling therapy in under resourced neonatal units in Africa, and other low-income countries.

The Helix trial is a two arm un-blinded pragmatic randomised controlled trial of whole body cooling versus standard care, after neonatal encephalopathy in low and middle-income countries. The investigators plan to randomise 408 babies in this trial, for which the investigators anticipate approximately 1200 babies will have to be screened for eligibility. The treatment duration (cooling therapy) is 72 hours, however the temperature of all recruited babies will be monitored during the first week after birth. Any temperature rise over \>37.5°C will be active treated, both in the cooling and usual care arms, as fever increases the brain injury and adverse outcomes after neonatal encephalopathy. The neurological outcomes will be assessed between 18 to 22 months of age. The trial duration will be 4 years, consisting of a 4 week start up period, 24 month recruitment period, a 18 month follow-up period, and 5 months for data analysis and write up.