Global and national burden of tracheal, bronchus, and lung cancer attributabled to household air pollution from solid fuels in populations aged 55 and above: an integrated study of frontier and joinpoint regression analysis | BMC Public Health

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The map of TBL burden attributable to HAPSF

In 2021, significant disparities in death and Disability-Adjusted Life Years (DALYs) of TBL burden due to household air pollution from solid fuels (HAPSF) were noted across 204 countries. The Democratic People’s Republic of Korea reported the highest death (40.49; 95% UI: 22.13–63.59) and DALYs (943.42; 95% UI: 513.45–1494.50), while the United Arab Emirates had the lowest death (0.0000716; 95% UI: 0–0.0001193) and DALYs (0.0018; 95% UI: 0–0.0031), reflecting the correlation between low SDI and higher TBL burden (Fig. 1, Supplementary Table 1). Lower SDI regions like East, South, and Southeast Asia, as well as sub-Saharan Africa, exhibited higher TBL burden compared to high SDI regions such as North America, Western Europe, and Australia. The distribution of all variables is provided in Supplementary Data 5.

The trend of dalys over time globally and SDI

The global trend in DALYs for TBL (Fig. 2A) shows an average annual percentage change (AAPC) of -4.17%, with a steady decline from 1990 to 2019. This decrease accelerated notably between 2004 and 2015, peaking at -10.11% (2011–2015). However, a slight reversal was observed from 2019 to 2021, with an APC of 0.21%.

In low SDI regions (Fig. 2B), the AAPC was − 0.54%. The most significant declines occurred from 1996 to 2007 (APC: -1.14%), followed by a minor rebound from 2014 to 2021 (APC: 0.12%). For low-middle SDI regions (Fig. 2C), an AAPC of -1.47% was observed, with an accelerated decline from 2011 to 2014 (APC: -4.63%), stabilizing at a slower rate in later years.

In middle SDI regions (Fig. 2D), the AAPC reached − 4.94%, with the most pronounced decline from 2011 to 2019 (APC: -11.54%), although a slight uptick was seen from 2019 to 2021 (APC: 1.03%). High SDI regions (Fig. 2E) demonstrated the steepest decrease (AAPC: -7.16%), with declines accelerating from 2001 to 2015, reaching − 16.55% (2011–2015). A minor increase from 2019 to 2021 (APC: 0.11%) suggests a recent stabilization.

The detailed high SDI trend (Fig. 2F) aligns with an AAPC of -10.72%, with steady declines from 1990 to 2019, intensifying to -13.77% in 2001–2019, before a slight reversal to an APC of 1.30% from 2019 to 2021. These variations highlight differential progress and recent increases in DALYs in higher SDI regions, likely linked to demographic shifts, including aging. The detailed information of APC and AAPC is provided in Supplementary Data 1, 2.

The net drift of TBL and period effects based on the different SDI levels

Figure 3A demonstrates the net drift of TBL across different age groups in the global population, exhibiting a stable trend with an average annual change of approximately − 5%. This trend is consistent across both male and female subgroups. When examining low SDI regions, the average annual change remained close to 0, indicating minimal change in the burden of TBL. In contrast, low-middle SDI regions exhibited a slight decline with an annual change of -1. In middle SDI regions, the average annual change showed a slight increase with age: -6 at age 55 and − 4 in individuals aged 90 and above. In middle-high SDI regions, the annual change was sustained at -10, indicating a clear downward trend in TBL burden. Furthermore, high SDI regions showed an even more pronounced decline, with an average annual change of -12.5. Regardless of the country or region, both male and female subgroups displayed trends consistent with the overall population. The detailed information of net drift is provided in Supplementary Data 3.

From 1996 to 2021, the global rate ratio for TBL burden showed a significant downward trend, dropping from 1.0 in 1996 to 0.26 in 2021, with consistent declines across genders (Fig. 3B). In low SDI countries, the overall rate ratio remained stable at 1.0; however, male rates decreased slightly to 0.8, while female rates increased to 1.4 by 2021. Low-middle SDI countries experienced a more notable decline, with the rate ratio dropping to 0.6 overall (0.6 for males and 0.8 for females). Medium, middle-high, and high SDI countries showed consistent reductions in rate ratios to 0.25, 0.2, and nearly 0 by 2021, respectively, with no significant gender differences.

The age effects based on the different SDI levels

Figure 4A, based on an age-cohort-period model, reveals age-related trends in TBL incidence. Incidence rates increase initially with age, peaking between 65 and 69 years in low and low-middle SDI regions, and at 60–64 years in middle SDI regions. In contrast, middle-high SDI regions exhibit a continuous decline in TBL incidence with age. High SDI countries maintain low incidence across age groups (0–20 per 100,000), with a consistent pattern observed across both genders.

In the overall population, the risk ratio for TBL shows a declining trend with age, from 1.25 at age 55 to 0.23 for individuals aged 90 and above, consistently observed across genders (Fig. 4B). In low SDI regions, the risk ratio for males decreases slightly with age (1.0 to 0.9), while it increases for females (1.0 to 1.27). Low-middle SDI regions also demonstrate an age-related decline in risk ratio, dropping from 1.08 to 0.5 overall, with a more gradual decrease for females (1.08 to 0.75). Medium, middle-high, and high SDI regions show pronounced declines; in medium SDI regions, the ratio decreases from 1.25 at age 55 to 0.2 by age 95+, while middle-high and high SDI regions see reductions from 1.5 to 1.25 at age 55 to 0.1 at age 95+, respectively, consistent across gender subgroups.

The decomposition analysis of dalys about TBL from 1990 to 2021

Figure 5 presents a decomposition analysis of Disability-Adjusted Life Years (DALYs) about TBL from 1990 to 2021. Globally, as well as in certain Social Development Index (SDI) regions (excluding low and low-middle SDI), the DALYs in 2021 show a downward trend compared to 1990, particularly in the middle and high-middle SDI regions (especially in East Asia). Conversely, in low and low-middle SDI countries and regions, TBL-related DALYs are on the rise, with South Asia experiencing the most notable increase. Overall, population growth is the primary driver of the increase in disease burden, while epidemiological changes contribute to a reduction in disease burden, and aging has only a minimal impact on this burden, such as East Asia.

The frontier analysis of TBL burden attributable to HAPSF by SDI level

In the frontier analysis of TBL based on data from 204 countries and regions from 1990 to 2021, Fig. 6A shows that as the SDI value increases from 0.0 to 1.0, the burden of TBL generally decreases. Additionally, with each passing year (represented by the color of the points becoming progressively lighter), the TBL burden also declines annually. Subsequently, the analysis evaluates the potential of each country to improve the TBL burden using DALYs and the Social Development Index (SDI) (Fig. 6B). Considering the stage of development, the analysis identifies the 15 countries with the greatest deviation from actual values (those most likely to achieve real improvement): Haiti, Kiribati, Honduras, Zimbabwe, Myanmar, the Marshall Islands, Tonga, the Federated States of Micronesia, the Lao People’s Democratic Republic, Papua New Guinea, Vanuatu, Lesotho, the Solomon Islands, Cambodia, and the Democratic People’s Republic of Korea. Blue points represent low-SDI (< 0.5) countries, including Niger, Mali, Bhutan, Malawi, and Côte d’Ivoire, which have the smallest deviation from actual values (most closely aligned with the real situation). Notably, red points represent certain high-SDI (> 0.85) countries and regions that still show the greatest deviation from actual values at their current stage of development (indicating substantial improvement potential), including Austria, Japan, Lithuania, Taiwan, Japan, and South Korea. The detailed information of frontier analysis is provided in Supplementary Data 4.

Projecting the number and rate of TBL based on the dalys

Forecasting global DALYs for TBL by age group using the Bayesian Age-Period-Cohort (BAPC) model indicates a substantial decline by 2044, with the most significant reductions in the 70–74 and 65–69 age groups (Fig. 7). DALYs per 100,000 for the 70–74 age group are projected to fall from 122 in 2020 to 49 by 2044. In contrast, the population aged 95 and older is expected to see a minimal decline, dropping from 30 in 2019 to 0 by 2044. Gender-based projections suggest a greater decrease in DALYs per 100,000 for males compared to females by 2044.