Is research using the narcissistic personality inventory relevant for understanding narcissistic personality disorder?

The many faces of narcissism: Narcissism factors and their predictive utility

“…Some argue that specific subscales related to grandiosity and entitlement should replace the NPI altogether (Brown et al, 2009). Others suggest that the NPI should not be replaced because it accounts for more variance in trait narcissism than these individual sub-scales (Miller, Price, & Campbell, 2012), and has strong convergence with expert ratings of narcissistic personality disorder (Miller, Gaughan, Pryor, Kamen, & Campbell, 2009). …”

Detecting Linguistic Traces of Destructive Narcissism At-a-Distance in a CEO’s Letter to Shareholders

“…The prominence of the DSM-IV-TR definition is unsurprising given that narcissism first emerged officially as a mental disorder with the publication of DSM-III by the American Psychiatric Association in 1980 (Miller and Campbell, 2008). Miller et al (2009) draw attention to the ''notion that the DSM-IV NPD [Narcissism Personality Disorder] construct itself should be considered the gold standard by which all other conceptualizations of narcissism should be judged'' (italics applied).…”

The Structure of the Narcissistic Personality Inventory With Binary and Rating Scale Items

“…Of the studies that have used clinical samples, Miller, Gaughan, Pryor, Kamen, and Campbell (2009) found that outpatients' NPI scores were lower than those of undergraduate participants, despite clinical interviews indicating that the outpatients were more narcissistic. Similarly, Vater et al (2013) found that NPI scores of those who had received a diagnosis of NPD and those who were healthy controls did not differ.…”