The phrase "a persistent decline in" is correct and usable in written English.
It can be used to describe a continuous or ongoing decrease in a particular area, such as performance, sales, or health.
Example: "The company has reported a persistent decline in sales over the last three quarters."
Alternatives: "a continual decrease in" or "an ongoing drop in".
The second is a persistent decline in productivity growth over the last dozen years.
A persistent decline in the immigrant population could damage the overall Arizona economy, Ms. McLaren said.
The carmaker is suffering from a persistent decline in sales and is busily restructuring itself.
Outside Japan, they argue, no central bank would tolerate a persistent decline in prices.
But a swelling public debt and a persistent decline in prices and wages are raising fears that Japan's economic recovery could soon run out of steam.
What makes this particularly puzzling for scholars reared on the classical models of competitive economies is that all this happened despite a persistent decline in real interest rates.
After a disease duration of more than 1 year, a flatter but persistent decline in DXR-BMD and DXR-MCI was observed, corroborating the findings reported by Hoff and colleagues [ 1].
Hospitalization occurred during patients' emergency phase; according to international guidelines [ 37], hospitalization was needed on the bases of psychiatric and behavioral factors, including a rapid or persistent decline in oral intake or co-occurring psychiatric problems leading to medical instability, abnormalities in vital signs and laboratory tests.
Derby, 10th in the Championship, said they acted following a "significant, unexpected and persistent decline in results, team unity and morale".
Therefore, in addition to workload reductions explaining their persistent decline in work injuries, workforce composition biases may have been a main explanation for their lower fatality rate after the economic downturn.
