Chapter 5 124 5.3.3 Double threshold The single threshold dichotomy reported above had a binary outcome: referral for NPA or no referral. This is not consistent with clinical practice, where an intermediate strategy of ‘keeping the patient under observation’ or ‘active monitoring’ is often used. The use of two cut-off scores: <21 invitation for NPA, 21≤ active monitoring <26; no follow-up ≥26 gave a more differentiated result (columns B, F). The double-threshold MoCA as an add-on for suspected patients after initial assessment (column F) resulted in 5(2+3*) instead of 11 MD (column E) patients with MD not undergoing a comprehensive diagnostic route, without the increase in FP referrals. This resulted in the highest accuracy (89%), PPV (52%) and NPV (99%). However it would mean that 107 patients need to be reassessed. 5.4 Discussion Limited diagnostic resources and rising patient numbers present challenges in MD diagnostic procedures. It is necessary to differentiate patients to focus scarce diagnostic resources on those who need them most. Therefore, we compared different strategies, including a double-threshold MoCA. Our results confirm that an objective test can have added value. However, how and when the MoCA was used gave different results. All the strategies we tested were able to find most of the patients with MD. Judgement by only the TP/FN is not sufficient, as the FPs differs substantially (figure 1/table 3). Using merely initial assessment (column D) gave the highest TP of the compared strategies, but the high amount of FPs complicates the diagnostic route: still 42% of all assessed patients were referred for a comprehensive diagnostic route. This is probably because clinicians try to avoid FNs. Especially without the assistance of an objective test, clinicians tend to refer subthreshold states earlier. The single cut-off MoCA strategy did not solve the (sub)threshold dilemma. Although the low PPV and the very high NPV underscore that only a MoCA score above the cut-off (i.e., a negative MoCA) should be considered reliable and thus suitable to adjust clinical judgement, i.e., initial assessment (table 4d). Using a MoCA as a second-stage screener with a score of 21 or higher (cut-off <21) to adjust initial assessment (column E) reduced the FP referrals for an NPA by 65% (to n=72 of 290) but increased the FN by 3.6 times to 13% of MD (n=11).
RkJQdWJsaXNoZXIy MTk4NDMw