The phrase "a direct driver" is correct and usable in written English.
It can be used to refer to a specific factor or element that directly influences or causes a particular outcome or effect.
Example: "In our analysis, we identified a direct driver of employee engagement as the level of communication from management."
Alternatives: "a key factor" or "a primary influence".
Product irreplaceability, however, was found to be a direct driver of brand loyalty.
Land use change in the form of urbanization is a direct driver affecting the provision of ecosystem services from forests.
Studies on multifunctionality sometimes consider heterotrophic diversity as one of the many components of multifunctionality10,18 rather than as a direct driver of ecosystem functioning.
Urban expansion is a direct driver of land change and cause serious shifts in socio-ecological relationships and the associated lifestyles.
Cool-season storm tracks appear to be a direct driver of hydroclimatic variability, leading to instances of see-saw like relationships with neighboring regions, such as in the mid-14th century.
From an economic perspective, purely economic strength (in terms of absolute growth) appears to enhance city attractiveness for residents, while the dynamics observed in research and development activities influences the quality of employment instead of being a direct driver of population growth.
Thus policies addressing direct drivers of change, in particular, need to take scale into consideration during their formulation.
Here humans are the direct driver of a loss of control which they tolerate.
However, "Order Food" is not a direct revenue driver for Facebook.
Thus, EBV does act as a direct epigenetic driver in normal and malignant epithelial cells.
EBV appears to act as a direct epigenetic driver for the pathogenesis of its associated tumors.
