The phrase "a previous study suggested" is correct and usable in written English.
You can use it when referring to findings or conclusions drawn from an earlier research study.
Example: "A previous study suggested that regular exercise can improve mental health."
Alternatives: "an earlier study indicated" or "a prior study proposed".
A previous study suggested that differences in HMEF design might contribute to filter obstruction under wet conditions.
A previous study suggested a possible relation between the relaxation obtained during the reflexology session and the sleep.
In this context, a previous study suggested that patterns of thalamocortical input could be used to identify thalamic nuclei67; specific combinations of cortical targets could be used as a standard for defining thalamic subdivisions.
A previous study suggested that episodic migraineurs have reduced pain thresholds in the 24 h prior to migraine onset [60].
A previous study suggested that syringic acid is the least toxic phenol compound (Rahouti et al. 1997).
A previous study suggested that the nodulation factor signaling pathway might proceed through an endocytosis process (Timmers et al. 1998).
Results of a previous study suggested that the risk of graft failue after transplantation of HLA-identical T cell-depleted marrow may be influenced by the preparative regimen.
A previous study suggested pain catastrophizing and catechol-O-methyltransferase (COMT) genotype influenced clinical pain ratings for patients seeking operative treatment of shoulder pain.
A previous study suggested that preoperative serum creatinine was a predictor for postoperative renal complications and in-hospital mortality in patient undergoing cardiac surgery [6, 21].
A previous study suggested that TRAF family members are involved in the regulation of inflammation and antiviral responses (Saha and Cheng, 2006).
A previous study suggested that biopsies of the gallbladder, bile duct, and liver are useful for diagnosing IgG4-related cholecystitis [19 22].
