The objective of this study was to establish the non-inferiority of an oral enzyme therapy (Phlogenzym-(PE)) as compared to the non-steroidal anti-inflammatory drug (NSAID) diclofenac (DC) in patients with osteoarthritis (OA) of the hip.
Ninety patients presenting with painful episodes of OA of the hip were treated for 6 weeks in one study centre in a phase III, randomised, double blind, parallel group trial. Altogether, 45 patients were treated in the PE group and 45 patients were treated in the DC group. Primary efficacy criteria were: WOMAC dimensions pain, joint stiffness and function, and Lequesne index as multiple endpoint according to O'Brien. The efficacy criteria were analysed applying the test of non-inferiority with regard to mean changes and frequencies, t-test, U test, ANCOVA and descriptive methods.
Within the 6 weeks observation period, the adjusted changes from baseline to endpoint of the target parameters worked out as follows (adjusted differences, mean +/- SEM): WOMAC subscale pain (PE -10.3 +/- 1.2, DC -9.5 +/- 1.2), WOMAC subscale joint stiffness (PE -3.9 +/- 0.5, DC -3.6 +/- 0.5), WOMAC subscale physical function (PE -31.7 +/- 3.5, DC -29.7 +/- 3.5), Lequesne's index (PE -2.89 +/- 0.47, DC -2.27 +/- 0.47). Non-inferiority of PE as compared to DC with regard to the O'Brien's global sum of the standardised adjusted changes from baseline to endpoint in pain, stiffness, physical function, and Lequesne's index was established with p = 0.0025. PE was simultaneously non-inferior as compared to DC with regard to the 4 single endpoints: WOMAC subscale pain (p = 0.0033), WOMAC subscale joint stiffness (p = 0.0061), WOMAC subscale physical function (p = 0.0039), Lequesne's index (p = 0.0008) (closed test procedure). The equivalence tests remained insignificant due to comparatively lower effects of DC. For 71.1% of the PE patients and for 61.4% of the DC patients rates of good or very good global investigator assessments of efficacy were calculated (test of non-inferiority: p = 0.0011). In the majority of patients, tolerability was judged in both drug groups as very good or good.
This trial showed significant non-inferiority from 6 weeks treatment with PE in patients with OA of the hip with regard to the WOMAC dimensions pain, stiffness and physical function, to Lequesne's index, to the investigator and patients assessments of efficacy, and to the responder rates based on pain, physical function, and patient assessment of efficacy. With regard to drug tolerability some tendencies in favour of PE were detected. However, in this study there was no real difference between PE and DC 100 mg/day, implying an equal benefit-risk relation between the substances. PE may well be recommended for the treatment of patients with osteoarthritis of the hip with signs of inflammation as indicated by a high pain level.