Evaluation of a method for assessing potent analgesics

Abstract

In a retrospective analysis of data which evaluates the influence of various factors on the outcome of a clinical assessment of potent analgesie drugs, (1) the method of assaying success of treatment, (2) the influence of different observers in the results obtained, (3) the influence of other factors, viz., age, sex, and weight of the patient, site and duration of operation, and initial severity of pain, were considered. It was concluded that methods based on the subjective assessments of either the patient or observer were valid and sensitive. Changes in spirometrie measurements following treatment were not in themselves valid indices of pain relief, but may be of value in certain circumstances. There was good correlation between the different observers' estimates of pain relief. Low pain severity before treatment was associated with a high er rate of placebo response than was severe pain. Age, sex, body weight, and duration of operation were without significant effect.

Controlled Comparison of the Efficacy of Fourteen Preparations in the Relief of Postoperative Pain

“…The method has been previously described and presented with a critical assessment of its sensitivity and validity (Loan et al, 1968). Patients who had undergone upper or lower abdominal surgery were admitted to the trial when the nursing staff considered that they required their first postoperative analgesic.…”

Management of pain after abdominal surgery: dipyrone compared with pethidine.

“…Possible major sources of error, such as bias, procedural changes and different investigators (Loan, Morrison & Dundee, 1968) were overcome using double-blind method, strict adherence to the protocol and the use of the same investigating personnel. Errors arising from the patient population (Loan, Morrison & Dundee, 1968) Time after administration (h) Figure 4 Mean relief scores in patients with initially severe pain: 0, dipyrone; 0, pethidine.…”

“…Errors arising from the patient population (Loan, Morrison & Dundee, 1968) Time after administration (h) Figure 4 Mean relief scores in patients with initially severe pain: 0, dipyrone; 0, pethidine.…”

Pentazocine

“…In other between-patient trials pentazocine has been compared with morphine (Stoelting, 1965;Wallace, 1970), pethidine (Sadove and Balagot, 1965), in relatively small numbers of unselected postoperative patients (i.e. a population that not infrequently includes patients who have low initial pain and a higher rate of placebo response than those with severe pain [Loan et al, 1968]). As there are no completely satisfactory objective criteria available to assess pain relief, pain severity must be clinically assessed before and after treatment by the subjective estimates of the patient and a trained observer.…”

“…Measurement of changes in vital capacity (Ve) and peak expiratory flow rate (PEFR) have been used in an attempt to objectively assess changes in pain intensity, but difficulty arises in expressing spirometric changes in a meaningful manner. Conaghan et al (1966) considered that VC measurements revealed a 'dependence of analgesic response to initial pain in a quantitative fashion not possible with any scoring system' whereas Loan et al (1968) reported the failure of spirometric measurements to distinguish between saline and morphine 10 mg in patients with pain resulting from abdominal surgery, when subjective methods detected a highly significant difference (p < 0.0005) . Obviously, as mentioned by Hill et al (1967), measurements ofPEFR weigh against drugs producing most respiratory depression and may not truly reflect the degree of analgesia.…”