Introducción

Neuropsychiatric symptomatology (NPS), defined as the presence of hallucinations and delusions occurring during consciousness, frequently accompanies Parkinson’s disease (PD).1,2 Rates between 20 and 30% have recently been reported.3 Its appearance causes an increased workload for the caregiver (CG)4, 5 and is often the prime cause of institutionalization.3, 5

 

For this evaluation we used, among other psychometric tools, the Neuropsychiatric Inventory (NPI)6, which was originally designed to evaluate NPS in patients with dementia.7 The original version was later developed into a shorter format (NPI–Q)8, and re–designed for self–rating by the caregiver. The most recent version has twelve parameters, each scored on a scale of 0 to 3 points, with zero indicating the parameter’s absence and three reflecting its most severe form. Thus, a total score of 36 points would indicate maximum severity in all parameters considered.

 

We used a Spanish version of the NPI–Q9, that showed a correlation of the Pearson coefficient(r = 0, 89) in the test–retest analysis and convergence in the NPI (Pearson’s correlation r = 0,879) with the gravity scale.
 

In a study carried out by Aarsland et al6 in which the NPI was used, the authors found that patients with Parkinson’s and dementia had a more severe NPS score when compared with non-demented or questionably demented patients with Parkinson’s disease.
 

Thus, questions arise as (i) in what way can information from the CG (defined as the person in charge of the patient and the one having closest contact with the medical team10, be correlated with that supplied by the patient, and (ii) to what extent a tool that was originally designed to evaluate the NPS in demented patients, can also be applied to patients without dementia or even to non–dementia subjects suffering from Parkinson’s (NDP) This study was designed to answer these questions.
 

The topic is of considerable importance as it is wellknown that not all patients have adequate supervision and hence they are reluctant (or completely unwilling) to discuss their symptoms with the CG11. The main objective of the study was to determine the level of agreement between the responses acquired by the CG with those acquired directly from the NDP patient. To achieve this objective, an analytical (one point) study was designed to determine the consistency between the CG and NDP responses to NPI–Q scores.
 

 

Patients, materials and methods
Seventy patients diagnosed with PD were selected according to the criteria of the United Kingdom Parkinson’s Disease Society Brain Bank (UKPDSBB).12 Patients were selected randomly from those visiting the Movement Disorders outpatient clinic of the Neurology Service of the Carlos Andrade Marín Hospital (HCAM) in Quito, Ecuador.
 

Adequate sample size was determined to be 54 patients, calculated using the following equation13: n = z(2) [p(1-p)/e(2)] : 95% level of confidence (z = 1.96); 10% prevalence (p = 0.10), 92% preciseness (e = 0.08) . n = 1.96(2) [0.10(1-0.10)/0.08(2)] = 54 patients.
 

All the patients were evaluated in the period known as ON: the best functional situation. Patients with any of the following conditions were not included in the study: those with a record of psychiatric illness, illiterate patients, those currently suffering from any serious concomitant illness, amputees, and those with a score of < 24 in the Mini Mental Status Examination (MMSE),14 Spanish version,15 regarded as an indicator of the onset of dementia.16,17

 

Other patients’ conditions were also evaluated: the level of sections I, II and III of United Parkinson’s Disease Rating Scale (UPDRS)18, the state of the illness Hoehn and Yahr staging (H&Y)19, and daily activities (Schwab and England (S&E)20. Later in the study, the NPI–Q Spanish version9 was employed, first with the CG alone and subsequently, with the individual patient alone by a researcher with no knowledge of the previous result from the CG.
 

This study was approved by the Teaching and Research Management at the HCAM; and each participating patient provided their informed written consent. The CG had demographic information about the patient, information about how many other patients shared the room with the patient in the study and, if the patient was married, how many shared the bed. The weighted kappa correlation coefficient was measured to evaluate the CG–NDP consistency rate (Test–retest reliability; obtained by judging the reproductibility or stability of a instrument over time; two or more observers; or two or more times); a value of 0.7 or higher was accepted as significant21. If CG–NDP correlation results were found to be insignificant, a post-hoc analysis was performed.

 

Finally, because a relation between increased neuropsychiatric disturbance and the H&Y stage was found (Aarsland et al6 and Fenelon et al22) we study the convergent validity (Validity–Construct–related, include examining the logical relations that should exist with other measures, know too as convergent validity) analyzed using the Spearman rank correlation statistic values greater than (r <0.29 are weak correlations; r <0.3–0.58 are moderate correlations and; r < 0.59 are high correlations the convergent validity).23 The total of NPI–Q for the CG and the NDP were compared according to degree of sickness: H&Y, S&E and UPDRS (I, II, III sections and Total).

 

 

Results
Seventy patients were sampled: 54 were male, 16 were female with a combined average age of 70.5 years. Thirty eight patients had attended primary school. On average, patients had suffered this disease for a period of six years with L–dopa therapy during 5 years and activities of daily life activities (S&E) of 70%. Their scores in the MMSE averaged 26.7 and 61 in the first three sections of UPDRS. (Table 1)
 

According to information from the CG, 38 patients were husbands or wives 23 were children, and the other nine were nephews or nieces, distant relatives or friends. Thirty eight patients were elementary school students, 27 were secondary school age and eleven were high school students. Of the 70 patients, 46 shared their home room (thirty seven couples, eight children and one employee); thirty of the couples shared the same bed.
 

The score of the NPI–Q based on the CG was between 0 and 26, with an average of 10.57; 85.7% of the patients had a score less than 18. The patients gave themselves an average score of 12.59 and a rank between 2 and 25; 88.5% achieved a score of less than 18. It was obvious that in scores from both sources, CG’s and the patients themselves, parameters that reflected mood, apathy and irritability contributed the most to the total score (63.5%) to the CG’s score; and (73.8%) to the patient’s own score. It is important to point out that these parameters have to do with the mood of the patient and are not necessarily present in psychosis.

 

Table 1: Descriptive characteristics of the sample Mean values and standart deviation

 

The low kappa values obtained (Test–retest reliability) revealed that there is no consistency between the CG and the NDP scores (Table 2).
 

When the Spearman’s correlations were examined as a measure of converging validity of the NPI–Q (total score), based on the scales mentioned above, the values obtained on the NDP were more significant consistency than the ones obtained on the CG (Table 3).

 

Table 2: Inter – rater correlation (kappa) < 0.7 as significant

 

 

Discussion
The low kappa values obtained revealed that there is no consistency between the CG and the NDP. Thus, we were forced to question the relevance of the information provided to us by the CG and its value. Also, the NPI–Q was not designed specifically to measure psychosis in the PD (many parameters reflected mood, apathy, irritability, sleep disturbances or eating disorders), the only test speci- fic to the PD is the Parkinson Psychosis Rating Scale.24
 

Our results support that the NDP is the best source of information because his/her data allow us, for example, to quantify the UPDRS, to quantify quality of life, and to evaluate psychotic symptomatology. As well, it has been shown that the patient may choose not to talk about all that is happening in his/her body and mind to the CG in order (i) not to worry this person or not to appear “crazy,” (ii) for not considering the matter important, (iii) because he/she doesn’t trust the CG or (iv) simply because the CG isn’t quite observant enough.11,22,25

 

Correlations between sleeping disorders and hallucinatory and delusionary elements have been previously described.22 Incongruities were found and patients were considered to have the best inter– tem correlation (0.44). We conclude, therefore, that their information is the most consistent. Similarly, the patient’s values for convergent validity are better, probably because this information is given directly by the NDP. As well, similarities occur due to correlation with the motor test (third section of UPDRS) which is not influenced by information derived from the patient.
 

Here we present three hypotheses to justify the lack of agreement in the correlation between CG and NDP values: (i) many hallucinations, especially simpler ones, do not cause serious impact on patients and are heavily under-reported (only 1% are reported by patients22), (ii) many patients do not report such events in order not to sound “crazy” or “insane” or not to worry their relatives, or because they don’t think they are important. It is important to be aware of the discrepancy between spontaneous reports of hallucinations (1% of patients) versus reports of hallucinations following direct questioning to determine their occurrence (20–30% of patients)22; finally, (iii) we believe that the MMSE is not the best way to determine the absence of dementia in Parkinson’s patients because it over–emphasizes memory disorders that are symptoms of Alzheimer’s disease, and that the cognitive disorders of Parkinson’s are more circumscribes to the executive function as been previously described.26,27 As a result, patients that suffer Parkinson’s with dementia but who are not sensitive to MMSE might not be distinguished under this testing protocol.

 

Table 3: Spearman correlation (rho) *significant correlation (p<0.05 = 2 tyles=) ** significant correlation (p<0.01 = 2 tyles=)

 

As a result of this study, we conclude that the NPI–Q carried out by the CG is not the best tool to value NPS in non–dementia patients with Parkinson’s disease. It would be valuable to follow–up this evaluation with a higher number of NDP’s using other psychometric tools to evaluate cognitive function.
 

 

Acknowledgements
We thank Merche Boada, MD and the ACE Foundation (Barcelona, Spain) for providing us with the Spanish version of NPI–Q; and Margaret Stern, PhD for their editorial assistance.

 

 

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