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Measurement of a moment versus one or two weeks

Posted by PeterPrudon on 10 Oct 2012 at 09:43 GMT

The instruction for using the VAMS in this investigation was: "You can answer the following question by placing a cross on the line from 0 to 10: at the moment I feel …"
In other words, the patients are asked for a more or less random impression of their present mood, which is a rather fluctuating thing during the day and during the weeks. I think this is problematic for the following reasons:
1) If all patients would have taken this instruction literal, then their score necessarily would have been only remotely related to whatever other variable because of the fluctuations mentioned above. This weakens the predictive validity of the VAMS.
2) However, each patient may have his own idea of how much time is covered by "at the moment". So a few will think of the last half hour, other ones will think of the last hour, and so on. This is a factor attenuating the standardization of this VAMS.
3) Patients, nowadays, have experience with filling in questionnaires for diagnostic ends, so many of them will understand that it makes little sense to rate their mood for only a short instant. So they do not take the instruction too literal. Some of them will make their rating an expression of the last few days, others of the last week, still others of the last two weeks, and so on. This is another factor attenuating the standardization of this VAMS.
As far as I know the Hamilton equally suffers from the absence of a clear instruction as to the period to be covered by the questions, whereas Beck's Depression Inventory covers explicitly the last two weeks and the Edinburgh Depression Scale (only 10 items!) asks for the last week (Cox et al., 1996).

So it might be interesting to repeat this investigation with clear instructions about the period to be covered by both this VAMS and the parallel test(s) to be used.

Cox, J.L., Chapman, G., Murray D., Jones, P. Validation of the Edinburgh Postnatal Depression Scale (EPDS) in non-postnatal women. Journal of Affective Disorders, 3, 185–9.

No competing interests declared.

RE: Measurement of a moment versus one or two weeks

GDvanRijsbergen replied to PeterPrudon on 15 Oct 2012 at 12:18 GMT

Thank you very much for your comment.

Indeed mood is assumed to be a constantly fluctuating construct. The remarkable finding of this paper is that single-moment mood was predictive of relapse over 5.5-years in remitted recurrently depressed patients.

Patients were clearly instructed to rate their present mood on the VAMS. We have no indications that patients filled-out the VAMS with a different time-frame in mind, however it might be possible that there were individual differences on this while filling out the VAMS. Still, the two VAMS scales were moderately associated at baseline and after three months, demonstrating some stability over a three month period.

However, as in other clinical assessments, the time-frame patients actually have in mind when answering a question is hard to verify. Although the EDPS covers an explicit period of 10 days (and the HAM-D a week), a patient might have had one or more predominant bad days in mind that occurred before the time period covered by the measure. We agree with you that this limits the standardization of the VAMS, although we feel that other measures (including the EDPS) do not overcome this limitation.

We are currently studying the repeated assessment of mood using the VAMS in a large group of remitted recurrently depressed patients. Hereby, we will be able to study fluctuations in mood during follow-up. It could be that mood after remission is more stable than previously thought. In line with your suggestion, it would be interesting to study whether different instructions of the VAMS (i.e. last hour, last week) also lead to different results.

No competing interests declared.

RE: RE: Measurement of a moment versus one or two weeks

PeterPrudon replied to GDvanRijsbergen on 17 Oct 2012 at 14:22 GMT

Thank you for this further clarification. Your instruction must have decreased the likelihood that the patients differed much in the time-frame they had in mind. However, from a single-moment mood assessment can still not be much expected. The repeated assessment you are currently studying seems more promising for prediction, especially if you average the scores over a period. I am curious what difference it will make.

No competing interests declared.