Hi Joel,
I would be interested in reading some references on
VAS and how much of a change there needs to be for it
to be improving. We (3 podiatrists) use the VAS quite
a lot to help measure improvement. In the big picture
though, shouldn't we really be aiming for zero on the
VAS for the patient to be improving or improved??
--- Joel Radford <[log in to unmask]> wrote:
> Dear Paul,
>
> Yes, I agree that the patients in the ESWT trial
> have not improved by
> treatment.
>
> However, your statement that the "VAS is a very
> crude method of measuring
> anything" may not be accurate. I'd be interested in
> the references of the
> studies you're referring to.
>
> As far as I know, the VAS has long been accepted as
> reliable and valid
> measure, particularly for pain:
>
> - Revill et al (1976) found in 39 participants high
> correlations between
> measurements of remembered pain (r=0.97 to 0.99).
> - Scott and Huskisson (1976) demonstrated that the
> VAS does not differ
> significantly from a uniform distribution when 100
> patients were assessed
> for pain.
> -And Price et al (1983) demonstrated high between
> session reliability
> (r=0.97) for 50 participants who received pain
> evoked by heat pulses. In
> addition 30 of these participants had chronic back
> pain and were able to
> easily scale the intensity of their pain at its
> minimal (20mm), usual (49mm)
> and maximal levels (72mm) on a 15mm VAS.
> -Also, the frequent use of the VAS in clinical
> trials across most medical
> fields demonstrates its apparent responsiveness to
> change.
>
> If anyone is interested in what change on a visual
> analogue scale is needed
> before a patient can be seen to be improving I could
> provide some references
> for that too.
>
> Kind regards,
>
> Joel.
>
>
>
> Price, D. D., P. A. McGrath, et al. (1983). “The
> Validation of Visual
> Analogue Scales as Ratio Scale Measures for Chronic
> and Experimental Pain.”
> Pain 17: 45-56.
>
> Revill, S. I., J. O. Robinson, et al. (1976). “The
> reliability of a linear
> analogue for evaluating pain.” Anaesthesia 31:
> 1191-1198.
>
> Scott, J. and E. C. Huskisson (1976). “Graphic
> representation of pain.” Pain
> 2: 175-184.
>
>
>
> -----Original Message-----
> From: A group for the academic discussion of current
> issues in podiatry
> [mailto:[log in to unmask]]On Behalf Of Paul
> Conneely
> Sent: Sunday, 5 September 2004 5:56 PM
> To: [log in to unmask]
> Subject: Re: BJP Paper and Orthotic Evaluation
>
>
> Dear All
>
> The VAS is a very crude method of measuring
> anything. Studies regarding
> the reliability and Validity of VAS and thus
> accuracy of the VAS indicate
> that this measuring method is 'crude' at best.
>
> A P value of 0.04 suggests that there is a 4%
> probability that chance is
> involved in the treatment, that is they got better
> of their own accord.
>
> When applying the miniscule changes to the VAS that
> these patients have
> over three month period, one can conclude that they
> have not improved by
> treatment but by time.
>
> Paul Coneely.
>
>
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