This is the first study to estimate the costs and health effects of a screening program for neonatal hearing impairment in the developing world. Factors such as limited funding, shortages of manpower, and the inadequate provision of follow-up and support services have prevented the implementation of the NHS program in the vast majority of developing countries 
. Although the study design used here was similar to those of some previous research approaches in developed countries 
, this study considered not only direct indicators such as the number of infants diagnosed and who received an intervention but also DALYs averted. The advantage of calculating costs per DALY averted is that it allows a comparison to be made with other interventions and other regions. Such the indicator comprehensively measures the disease burden averted by the screening program at different options and conditions.
The goal of the NHS program in China is to establish a nationwide hospital-based universal program and to continuously expand diagnosis and intervention services 
. The rationale for implementing a universal strategy is that it can detect more deaf infants, providing a greater opportunity for them to experience normal language development, while also providing overall benefits in terms of the reduction in disability and the improvement in health and well-being of the Chinese population. Conversely, our results at a national glance seem to prove the targeted strategies were more cost-effective than the universal strategies. Does it mean that the MOH's plan is too ambitious to achieve at the moment? The answer depends on a huge geographical gap on the socioeconomic status. The screening program adopted in China is similar to that in developed countries; while compared to the implementation in those developed countries, the coverage of the screening program is diversified by regions with different socioeconomic status and the EHDI rate among the children with PCEHI is much lower and there remains a huge regional diversity in terms of implementation. The decision making in China is more complicated, as policy makers face key issues in the selection of the strategies and the protocols after the launch of the national policy for the scale-up. Therefore, our study provides a reference to different regions rather than a standard guideline after the launch of the national policy to scale up the screening program.
of sensitivity analysis suggests that not only the program coverage, but also the accessibility of the consequent diagnosis and intervention services after screening, are key factors for the scale-up of the program. At the regional level, these factors tend to parallel to the diversified regional socioeconomic status. The decision making should depend on the regional conditions: current implementation and accessibility of related services, as well as feasibility based on health resources in financial, human resource and material aspects. The study indicated that the optimal path for the scale-up is targeted OAE, universal OAE and ultimately universal OAE plus AABR. Targeted OAE plus AABR should not be considered due to the expensive ICER, underlying which is a limited beneficial population, caused by the targeted strategy. For the scale-up from the targeted to the universal strategies, the beneficial population needs to be expanded to more than 20%. Therefore, for those regions the current implementation cannot reach such the proportion of the beneficial population, particularly in rural and remote areas, targeted OAE is feasible.
In those regions currently targeted OAE is dominated, public investment to the related services for detection and rehabilitation is crucial to improve the cost-effectiveness of the universal strategies with better health outcomes, particularly universal OAE plus AABR. Compared to screening by OAE alone, the protocol of OAE plus AABR with better sensitivity and specificity saves costs by the false positive and detects more PCEHI cases. ICER falls down and becomes extremely close to universal OAE, as the program coverage and accessibility of detection and rehabilitation services increase, suggesting a good cost-effectiveness of the option. By increasing financial investment, it will avert more disease burden and have better monetary benefits. Therefore, in long-term, Universal OAE plus AABR should be the ultimate goal of the scale-up.
After the launch of the national policy to scale up the screening program, coverage of the screening program has significantly increased with the political commitment. On the other hand, availability of the related services for detection and rehabilitation remain as a “bottleneck” for the scale-up. Medical costs for diagnosis and interventions tend to be catastrophic and need to be fully covered by medical insurance or aid rather than an out-of-pocket payment. According to our pilot studies and the national statistics, the patient costs for diagnosis and intervention services exceeded about 10 times of the annual household expenditure 
. Moreover, ensuring human resources needs a long-term effort 
. In China, the audiologist and the specialist in hearing rehabilitation is of severe shortage, constraining the scale-up and the quality of intervention services. Until 2008, the total number of audiologist and specialist in hearing rehabilitation was only about 100, far from the real need of the professional rehabilitation services for about 1,500,000 people with hearing impairment 
Our study was restricted by a limited availability of data and evidence. First, although several scientifically sound studies demonstrated the benefits of early detection and intervention on speech and language outcomes, there is no study on the long-term psychological and educational outcomes and consequently the long-term benefits of the program cannot be exactly evaluated. Moreover, in China, there is lack of population-based study to survey the epidemiological situation of PCEHI in the national level. Data on the prevalence used in this study derived from crude estimation based on the number of hearing disable population and our pilot studies for the implementation of the screening program. Last but still important, the disability weight is not specified by severity of hearing impairment and only accounted for adult-onset hearing loss. The prevalence in different severity is not available in China, we cannot take consideration of this factor, which potentially has an impact on language outcomes 
In conclusion, to achieve cost-effectiveness and best health outcomes of the NHS program, its benefit population should be expanded by improve the accessibility of screening, diagnosis and intervention services. Depending on the program coverage and the availability of the related services for detection and rehabilitation, the universal strategies would be dominated in the developed provinces where screening, diagnosis and intervention services benefit over 20% of children with the disorder. In other regions, targeted OAE is temporarily more realistic, and related services need to reach 7% of the beneficial population. The regional policy makers should prioritize the investment to the related services for detection and rehabilitation and have an endeavor to improve its accessibility. The reference data from this study are thus expected to be of particular benefit in terms of the ‘rolling out’ of the national plan.
What is already known on this topic
The neonatal hearing screening program reduced the age of detection of child-onset hearing impairment significantly and made early hearing detection and intervention possible. The universal strategy has good cost-effectiveness in developed countries and has been widely applied.
What this study adds
In China, the accessibility of screening, diagnosis and intervention services diversified in different regions, leading to different cost-effectiveness of strategies and health effects. To achieve cost-effectiveness and best health effects, its benefit population should be expanded by improve the accessibility of those related health services.