The TN STEMI Program was a multicenter, prospective, observational study conducted in Tamil Nadu, India, that assessed the effects of implementing the STEMI India Model for the management of STEMI. We discuss the economic and societal impact in this article. Given that the intervention resulted in an absolute mortality reduction of 3.4%, we calculated a number needed to treat of 30 patients. At an annualized project cost of INR 15.11 million, this approximately calculates to INR 193,749 (USD 3,311) per life saved. The utility of the TN-STEMI Program can be estimated to be 1,108 life-years. This calculates to approximately INR 13,643 (USD 233) per life-year saved. Our estimates will likely be of particular interest to policy makers in low and middle-income countries, where financial and resource constraints pose a perennial public health challenge.

Ischemic heart disease remains the leading cause of disability and premature death across the globe. Its burden is rising disproportionately among lower- and middle-income countries (LMICs) and populations; it is estimated that 80% of all cardiovascular deaths now occur in LMICs [

A hub-and-spoke model (the STEMI India Model) was developed to attempt bridging these gaps.

The TN STEMI Program was a multi-centre, prospective, observational study conducted in Tamil Nadu, India, that assessed the effects of implementing the STEMI India Model for the management of STEMI [

Having established the feasibility and potential mortality benefit of implementing such a strategy, it is helpful to consider both the actuarial and estimated costs of implementing such a strategy in other settings. The implementation of the pilot project was funded by STEMI India, a non-governmental organisation, and by the Indian Council of Medical Research. Over a period of 319 days (10.6 months), the total implementation costs incurred (in 2013 INR) were Rs.13.2 million (annualized cost Rs. 15.11 million, or USD 258,268 at the annual average exchange rate in 2013) [

COSTS | |
---|---|

Devices | 5.63 |

Software & Servers | 1.70 |

Telecom & IT | 1.68 |

Operations | 4.11 |

Logistics | 0.39 |

Overheads | 1.59 |

Given that the intervention resulted in an absolute mortality reduction of 3.4%, we calculated a number needed to treat (NNT) of 30 patients. Considered differently, if we annualize the enrolment of patients in the post-implementation arm, it would mean that implementing this protocol resulted in 78 fewer deaths. At an annualized project cost of INR 15.11 million, this roughly calculates to INR 193,749 (USD 3,311) per life saved.

We can similarly use data from this project to estimate the cost-utility (effectiveness) of such a program from a societal perspective. Typically, one would need to look at quality-adjusted life-years or similar utilities for assessing cost-effectiveness of such an intervention. This information is not directly available. However, as a crude indicator, we can estimate “life-years saved” based on the age at the instance of MI, and how long the patient would be expected to live based on prevalent life-expectancy rates, and assuming no other competing risks of death [

We can estimate the societal benefits even better from a productivity standpoint when we extrapolate this mortality difference in terms of net gain to the total economy due to the deaths averted. This can be considered as the sum of net present value of all future income of the patients at the instance of their index event [

The expected number of working years left for the patient at the instance j of heart attack T_{j} for men and for women is arrived at by adding, at each remaining year of the patient’s life (up to age 70, assuming that anyone older would not work), the probability that (s)he will both survive and be part of the labour force. The formula is as follows:

where:

_{j,t}

_{t}

_{j,t}

The data for labour force participation rate at age t _{t}

The LFPR (per 1000) for all persons of all ages according to usual status (principal and subsidiary) for Tamil Nadu is 454 [

The total numbers of men and women at age t in the labour force _{t}

The number of working years left T for men and women at age j is calculated as the summation of the product of probability of survival at a particular age and the WPR at that age for all ages from the present age until age 70 (as, with the assumptions above, T becomes 0 at age 70).

The present value of all expected future income for the number of working years left T is then calculated by adding up discounted labour income for T years as follows:

where

I_{0} is average labour income per capita in the present year

T is the expected number of working years for the average person in a particular age group

g is the annual rate of income growth

r is the social discount rate

In keeping with recent guidance by the World Bank, for low- and middle-income countries [

the discount rate (r) is set at 6%

and the annual growth rate for real income per capita (g) is set at 3%

The average labour income per capita I is calculated by dividing the labour share of GDP by the total number of employed workers:

where

s is labour share of GDP

w is total number of employed workers

The average GDP of India at current prices over the five years from 2010 to 2014, chosen as the study was conducted between 2011 and 2013, was INR 83,222 billion (USD 1,422.25 billion at the annual average exchange rate in 2013) [

The present value (PV) of income of all patients who died until the 1-year follow-up was calculated post- and pre-implementation. The decrease in the PV of lost income (income that did not happen because of death) from the pre-implementation period to the post-implementation period is the gain to the economy provided by the intervention. Annualising these numbers for 2,265 patients results in INR 228.7 million (USD 3.91 million) lost pre-implementation and INR 175.6 million (USD 3 million) lost post-implementation, which is INR 53.1 million (USD 908,000) gained in the economy due to the protocol.

A benefit of INR 53.1 million on an annualized project expenditure of INR 15.11 million translates to INR 3.52 gained for every rupee spent. A sensitivity analysis changing discount rates and growth rates in our calculations of the net present values of future incomes is set down in the table below:

Discount Rate | |||||
---|---|---|---|---|---|

4% | 6% | 8% | 10% | ||

Growth Rate | 3% | 3.8 | 3.5 | 3.3 | 3.1 |

6% | 4.1 | 3.9 | 3.6 | 3.4 | |

8% | 4.4 | 4.1 | 3.9 | 3.7 | |

10% | 4.6 | 4.4 | 4.1 | 3.9 | |

12.0% | 4.7 | 4.6 | 4.4 | 4.1 |

Given that the 10-year Indian government bond yield, a substitute for risk-free discount rate, was 6.6% at the time of writing and the baseline GDP growth rate for 2017–18 was 5.9%, a realistic cost benefit ratio is 3.98 [

As discussed above, these estimates will likely be of particular interest to policy-makers in LMICs, where financial and resource constraints pose a perennial public health challenge. From a global viewpoint, the WHO considers interventions to be cost-effective if they have ICERs that are less than three times gross national income (GNI) per capita [

Our calculations and the discussion above are not framed around the traditional form of cost-effectiveness measures such as incremental cost-effectiveness ratio (ICER) given that granular patient-level cost details were not available. However, our endeavour is to provide an estimate of the modular cost of implementing a program such as the TN STEMI Program

For LMICs, the sharp increase in mortality and morbidity from non-communicable diseases such as ischemic heart disease presents one of the biggest challenges to sustained economic growth in the 21^{st} century and beyond. Tragically, this is occurring despite tremendous strides in available management options for these conditions. For STEMI in particular, the current unstructured and highly inefficient system of management in most LMICs means that the gains from revascularization therapies noted in developed countries can seldom be achieved. Such a system puts the onus on patients (and their families), who are already in the throes of an MI, to have the wherewithal to present to the right hospital within the right timeframe and with the availability of immediate financial liquidity. We therefore believe that the large-scale adoption of a STEMI systems-of-care approach as studied in the TN STEMI Program represents a cost-effective investment for health systems to correct many such inequalities and social deprivation among this high-risk vulnerable patient population. Such investments will likely be repaid many times over in hundreds of thousands of lives saved each year, enhanced economic development, and strengthened global security.

The additional file for this article can be found as follows:

Calculation of expected number of working years left T(j) at age j by gender using survival rate and labor force participation rate. DOI:

The authors have no competing interests to declare.