It depends on whether the diagnosis in question meets the definition of a principle dx in accordance with the official coding guidelines. You cannot just pick out whatever diagnosis code you want. Can you clarify further in your question? As stated by the others, we must abide by coding guidelines in assigning the principle dx that is supported by the documentation.
Per official coding guidelines:
The circumstances of inpatient admission always govern the selection of principal diagnosis. The principal diagnosis is defined in the Uniform Hospital Discharge Data Set (UHDDS) as “that condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care.” -"what bought the bed-review the record in its entirety and determine which dx led to the decision/need for an inpatient bed.
B. Two or more interrelated conditions, each potentially meeting the definition for principal diagnosis. When there are two or more interrelated conditions (such as diseases in the same ICD10-CM chapter or manifestations characteristically associated with a certain disease) potentially meeting the definition of principal diagnosis, either condition may be sequenced first, unless the circumstances of the admission, the therapy provided, the Tabular List, or the Alphabetic Index indicate otherwise.
C. Two or more diagnoses that equally meet the definition for principal diagnosis In the unusual instance when two or more diagnoses equally meet the criteria for principal diagnosis as determined by the circumstances of admission, diagnostic workup and/or therapy provided, and the Alphabetic Index, Tabular List, or another coding guidelines does not provide sequencing direction, any one of the diagnoses may be sequenced first. et, etc.
CMS has stated direct quote ““We do not believe there is anything inappropriate, unethical or otherwise wrong with hospitals taking full advantage of coding opportunities to maximize Medicare payment that is supported by documentation in the medical record.” – Direct quote, CMS 2008 IPPS Final Rule, http://www.cms.hhs.gov/AcuteInpatientPPS/downloads/C MS-1533-FC.pdf, p. 208.”
As Kristen as stated below that yes there is a difference between maximizing and optimization. So what CMS is saying is they have no problem with hospitals optimizing those opportunities where the documentation and coding guidance are utilized. This discussion of the two are also included in the CICA exam (Certified Inpatient Coding Auditor) located from HFMA. They have a webinar recording that explains optimization and coding.
I believe the terms you are looking here for when accurately coding diagnoses and procedures that are fully supported by the medical documentation within the health record are reimbursement optimization verses reimbursement maximization. The later, reimbursement maximization refers more closely to Medicare fraud and abuse and would likely go against coding guidelines and principles since you are trying to maximize reimbursement to the highest level possible without regard to rules and regulations. An example would be coders, clinicians, and/or CDI specialists tweaking the principle diagnosis or adding wording/phrases within the medical documentation to support a certain diagnosis when there are no existing clinical indicators so that the patient encounter falls within a higher weighted DRG. Reimbursement optimization refers to the opposite, and a healthcare organization is legally entitled to seek out optimal reimbursement for the cost of care and level of resource utilization provided as long as it is fully supported by the medical documentation and follows coding guidelines and principles. An organization optimizes reimbursement by ensuring that the entire patient encounter is documented properly throughout the care continuum. This would include activities such as compliant queries, quality assurance, and performance improvement activities to ensure that documentation is accurate, consistent, comprehensive, timely, current, accessible, and reliable. An example of optimizing reimbursement would be a compliant query from a CDI specialist noting that there are clinical indicators within the health record that would support a different principle diagnosis, a different POA indicator (Y verses N), or overlooked CC/MCCs.
AHIMA's Data Quality Management Model is a great way to assess the quality of the documentation within the health record. This updated model (2015) for data quality includes Information Governance and Data Stewardship to ensure that your organization can optimize reimbursement through collecting, analyzing, and reporting, storing, managing, and maintaining data in accordance with all compliance policies and procedures.