In this study, the incidence of delirium assessed with the NEECHAM scale (20.3%) was comparable to the results of the CAM-ICU (19.8%). The diagnostic descriptives of the NEECHAM scale showed good results. Additionally, patients were classified in the different categories of the NEECHAM scale.
The research on intensive care delirium has taken a giant step forward since the development of assessment tools. A scale diagnosing delirium seems reliable when development was based on the DSM criteria. Hence, a confirmation by a psychiatrist is not necessary in daily practice. A gold standard for biological or physical tests, however, could be discussed . A standard implies a level of perfection able to judge over all other tests. This perfection could hardly be attained by an individual assessing the patient.
Although the delirium assessment instruments have often been used in research, the implementation as a standard medical or nursing screening tool has just started in clinical practice. The CAM-ICU, the Intensive Care Delirium Checklist, and the NEECHAM scale are available to screen for delirium. Nowadays, there seems to be no need for the development of new tools, but the existing instruments should be studied thoroughly and refined to achieve a global understanding of the assessment of the delirium syndrome .
The CAM-ICU was developed for physicians and researchers based on the DSM criteria  but now is available to be used by intensive care nurses. The screening can be implemented in the daily nursing care after limited training. The instrument is translated and validated in 10 different languages. Therefore, the CAM-ICU usually is considered to be the 'gold standard' for the diagnosis of delirium. The incidence rates of delirium assessed with the CAM-ICU showed a wide range. Ely and colleagues [4, 8] reported incidence rates of 83.3% and 87.0% in conscious medical or coronary care patients who were mechanically ventilated. McNicoll and colleagues  detected 31.1% delirium in medical intensive care patients older than 65 years, and Balas and colleagues  reported 28.3% in a surgical ICU. In our research, 19.8% of the mixed intensive care population developed delirium according to the CAM-ICU. The subgroup analysis of the internal medicine patients (Table 3) found an incidence of 26.5% in our population, but the other categories of patients developed less delirium. Our incidence rates assessed with the CAM-ICU seem to be lower than those of the published reports. This could be explained by the absence of ventilated patients in our population. Moreover, the architecture of the studied ICUs might play a beneficial role in the prevention of delirium (for example, the presence of visible daylight and a clock). Further research has to focus on the onset of delirium and the precipitating risk factors in the studied ICU.
The NEECHAM scale was developed as a nursing screening instrument for the early detection of delirium and was validated against DSM criteria for use in an ICU . In this validation research, 19.4% delirium and 15.8% mild confusion rates were found in a medium-sized ICU of a general hospital. The population in our study had a similar incidence for delirium but a higher incidence for 'mild confusion'. A report of Csokasy and Pugh , also using the NEECHAM scale, showed a total score of 47% for both categories taken together. The patients in their population (n = 19) were all older than 65 years and were admitted to an ICU of a smaller hospital. As already stated by Immers and colleagues , the evaluation of the physiological condition may not be relevant to the delirium assessment of the patient in the ICU. Since there has been no research or validation study to verify this suggestion, the assessment of the physiological condition will be retained as a basic element of this tool. Additionally, further study is needed to adapt and validate the NEECHAM scale for the delirium assessment of the intubated or the ventilated patient. Also, a longitudinal study needs to inquire whether the numbered approach and the different categories of the NEECHAM scale have a predictive value against a binary approach. Consequently, the categories 'at risk' and 'mild confusion' could have an additional value. Preventive actions eventually could protect patients from becoming delirious. As Devlin and colleagues  in their excellent review of delirium instruments for the ICU already remarked, all evaluations are dichotomous and therefore do not measure delirium severity.
Besides the NEECHAM scale and the CAM-ICU, the Intensive Care Delirium Checklist is a commonly used screening tool for the detection of delirium in the ICU . Incidence rates of 19.2% and 31.8% were reported in an adult population in a mixed ICU [24, 25]. Many items in this scale can also be scored by a nurse during daily practice. This eight-item scale also provides a numeric approach to the delirium assessment. Each item scoring positive gets one point. A score of four points was considered to detect 99% of the delirious patients. A definition of a population 'at risk' or with 'mild confusion' is not provided. A binary approach of the score was suggested. Given the four categories of the NEECHAM scale, the last one creates more opportunities to classify the patient.
Four positive CAM-ICU patients scored 'mild confusion'. Five patients scoring negative on the CAM-ICU scored delirious on the NEECHAM scale. Four of them had a borderline score on the NEECHAM scale. One patient had a score of 14 on the NEECHAM scale and was assessed as negative for delirium on the CAM-ICU. This patient received propofol (through a continuous intravenous infusion pump), which possibly influenced the results. The NEECHAM scale proved to be a good delirium screening instrument with a strong denial power. The specificity proved to be good in all categories. The diagnostic descriptives for the NEECHAM scale in the cardiac surgery group, in contrast to the results of the other categories of admittance, were low.
Nurses are the first caregivers to observe the patient and to detect an altering cognitive function. The NEECHAM scale uses the daily observation skills of nurses and their standard 24-hour monitoring of a patient in the ICU. The CAM-ICU needs a short visual or auditive test. Both scales, showing the same result in the diagnosis of delirium, could be considered for implementation in the standard nursing observation or monitoring in the ICU. The focus in research on intensive care delirium should shift from possible treatments to early prevention of the syndrome [26, 27]. The detection of patients in an early stage of confusion and the classification in categories could become an important advantage of the NEECHAM Confusion Scale [18, 28]. Therefore, a longitudinal study is needed.
Our study is limited by the size of the population in the different categories of admittance. Each category could be the subject of a further study. Both studied scales were validated and verified for the intensive care setting. For the purpose of this study, a confirmation of the delirious state by a psychiatrist seemed unnecessary. The patient was assessed once in the morning. The simultaneous assessment of both scales could have created an interscale bias. The result of the NEECHAM scale, however, was calculated only after the paired assessment of the patient. Assessment of the patient at least three times a day could be recommended. A standardized screening for delirium should contain one observation during each nursing shift and an additional score on suspected events due to the fluctuating nature of the syndrome. The incidence in this study could have been higher when more daily assessments were completed. In addition, no ventilated or intubated patients were included. These categories of patients often develop delirium. There is a need to test the NEECHAM scale in this population.