For many countries, including the full range from underdeveloped to highly developed countries, **no data about the number of surgeries per year is available.**

However, the 2008 Lancet publication *Weiser et al.*

*An estimation of the global volume of surgery: a modelling strategy based on available data*, DOI 10.1016/s0140-6736(08)60878-8

provides a simple method of roughly estimating this number.

According to table 2, countries can be assigned one of several expenditure stata regarding their health care spending, each with an assigned *Mean estimated **surgical rate per **100 000 population :*

- Poor-expenditure countries:
`295`

- Low-expenditure countries:
`2255`

- Middle-expenditure countries:
`4248`

- High-expenditure countries:
`11110`

#### How to classify countries:

According to the above-cited paper, the countries shall be classified by the **per-capita total yearly expediture on health**:

- Poor-expenditure countries: Less than
`100$`

- Low-expenditure countries: Between
`101$`

and`401$`

- Middle-expenditure countries: Between
`401$`

and`1000$`

- High-expenditure countries: More than
`1000$`

There are many source from where you can acquire this data. One of the easiest-to-use sources is the WHO country profile page. For example, you can see that Angola had a per-capity health spending of `51$`

in 2020. This clearly puts Angola into the Poor-expenditure countries considering our criteria above.

#### Calculation example:

Consider a middle-expediture country with a population of `22.8`

million inhabitants.

According to the formula above, a rough estimate for the number of surgical proceducers in said country can be calculated by:

\text{Number of surgeries} \approx \frac{\text{Population number}}{100000} \cdot \text{Middle expenditure mean surgical rate}Regarding our example:

\text{Number of surgeries} \approx \frac{22.8*10^6}{100000} \cdot 4248 = 968544Hence, we can *roughly* estimate that `968544`

surgical procedures are performed in said country per year.