The Economics of Longevity: Efficiency of Health Investments, Institutional Quality, and Carbon Emissions Across Income Groups in Sub-Saharan Africa – Implications for SDG 3

Background Sub-Saharan Africa (SSA) faces a paradox of rising health spending alongside persistently low life expectancy, raising fundamental questions about health investment efficiency. Understanding how institutional quality and environmental degradation shape that efficiency is essential for accelerating progress toward SDG 3. Methods The Simar and Wilson (2007) Algorithm 2 two-stage bootstrap Data Envelopment Analysis procedure is applied to 45 SSA countries over 2000–2023. Life expectancy is the output; government health expenditure per capita and mean years of schooling are inputs. A bootstrap truncated regression examines institutional quality, carbon (\(\:{CO}_{2}\)) emissions, electricity access, population ageing, and out-of-pocket expenditure as efficiency determinants. An income-group interaction framework tests whether institutional quality effects vary across income levels. Results The mean bias-corrected efficiency score is 0.866, implying a 13.4% average efficiency shortfall. Institutional quality significantly reduces efficiency among low-income countries (\(\:\beta\:=-0.105,p<0.01\)) but has no significant effect at higher income levels. \(\:{CO}_{2}\) emissions reduce efficiency (\(\:\beta\:=-0.047,p<0.01\)), electricity access improves it (\(\:\beta\:=0.005,p<0.01\)), and out-of-pocket expenditure reduces it consistently across all specifications. Conclusion Meaningful life expectancy gains are attainable through improved resource allocation without additional spending, directly supporting SDG 3.8. Governance reforms in low-income SSA countries should be carefully sequenced to minimize short-run efficiency costs. The climate-health efficiency nexus positions pollution control and clean energy as complementary health system priorities aligned with SDG 3.9 and SDG 13.