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PAPERS: Peter M. Haddad Antipsychotics and diabetes: review of non-prospective data The British Journal of Psychiatry 2004; 184: s80-86s [Abstract] [Full text] [PDF]

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Antipsychotics and diabetes: review of non-prospective data is not systematic

Micheal D Sriescoldu   (17 October 2004)

Antipsychotics and diabetes: review of non-prospective data is not systematic 17 October 2004
Micheal D Sriescoldu, Hospital Doctor University of Leeds Send letter to journal: Re: Antipsychotics and diabetes: review of non-prospective data is not systematic sriescoldu{at}hotmail.com Micheal D Sriescoldu	Dear Sir, I very much welcome Dr Haddad’s timely review of the important link between antipsychotic drugs and diabetes. His critical review appears thorough especially in its analysis of the many methodological problems in this area. However, I would like to highlight some areas where he may have strayed away from the principles of evidencebased medicine and also raise point he may himself like to comment upon. The first issue is Dr Haddad appears to confuse the terms “prospective”and “cohort” repeatedly saying that retrospective studies of limited value. Well designed, adequately sized, retrospective cohort studies can be very powerful where adjustment for possible bias and confounders have been considered. It is not so much the fact that they are conducted forward in time to capture new incident cases that is important (that is “prospective” versus “retrospective”) but rather that the study design assesses a defined group exposed to one or more putatative risk factors over some period of time (that is a “cohort” study).[1] Lets not forget that many important discoveries in medicine have involved retrospective methodology and retrospective cohort studies rank highly in many international guidelines on evidence based medicine.[2 ] The second issue is one of adequacy of the literature search. Commendably Dr Haddad states his search strategy in his article but electronic searches of medline alone are notoriously unreliable at finding all available literature in medical specialties.3 The result is that Dr Haddad appears to have unfortunately overlooked at least seven studies from drug safety databases published before 2003 [4 5 6 7 8 9 10] and at least one published in 2004.[11] In addition, I am not sure why Hadad considers the data in the WHO database to be “anecdotal”, whereas data collected in other databases to be “pharmaco-epidemiological”? [12] Of course, I accept that the study published in March 2003 would have appeared too late for inclusion but nevertheless analysis of fifteen studies changes the landscape of this review a little. In particular three studies not considered by Hadad compare the risk of diabetes in those taking Olanzapine with patients not taking Olanzapine.[7 9 10] and find an increased risk. Thus taking the data together, if 7 of 8 studies demonstrate an increased risk of diabetes with Olanzapine compared with those without, and the 8th negative study was sponsored by Lilly (as correctly pointed out by Hadad himself) would Peter Hadad still stand by his statement that “studies attempting to establish whether the association between atypical antipsychotic medicines are contradictory and inconclusive”? S. Sriescoldu References 1 Harbour R and Miller J for the Scottish Intercollegiate Guidelines Network Grading Review Group. A new system for grading recommendations in evidence based guidelines. BMJ 2001;323;334-336. 2 Upshur REG. Are all evidence-based practices alike? Problems in the ranking of evidence. CMAJ 2003; 169 (7): 672-673. 3 Hersh WR Medical informatics - Improving health care through information JAMA 2002; 288 (16): 1955-1958. 4 Lund, B.C., Perry, P.J., Brooks, J.M., Arndt, S. Clozapine use in patients with schizophrenia and the risk of diabetes, hyperlipidemia, and hypertension: a claims-based approach. Arch. Gen. Psychiatry 2001; 58, 1172–1176. 5 Biswasl, P.N., Wilton, L.V., Pearcel, G.L., Freemantle, S., Shakir, S.A. The pharmacovigilance of olanzapine: results of a post-marketing surveillance study on 8858 patients in England. J. Pharmacol. 2001; 15, 265–271. 6 Wang, P.S., Glynn, R.J., Ganz, D.A., Schneeweiss, S., Levin, R., Avorn, J. Clozapine use and risk of diabetes mellitus. J. Clin. Psychopharmacol. 2002; 22, 236–243. 7 Caro, J., Ward, A., Levinton, C., Robinson, K., Kopala, L., The risk of diabetes during olanzapine use compared with risperidone use: a retrospective database analysis. J. Clin. Psychiatry 2002; 63, 1135–1139. 8 Kornegay, C.J., Vasilakis-Scaramozza, C., Jick, L., Incident diabetes associated with antipsychotic use in the United Kingdom general practice research database. J. Clin. Psychiatry 2002; 63, 758– 762. 9 Gianfrancesco, F., Grogg, A., Mahmoud, R., Wang, R.H., Meletiche, D. Differential effects of antipsychotic agents on the risk of development of type 2 diabetes mellitus in patients with mood disorders. Clin. Ther. 2003a. 25, 1150–1171. 10 Gianfrancesco, F., White, R., Wang, R.H., Nasrallah, H.A. Antipsychotic-induced type 2 diabetes: evidence from a large health plan database. J. Clin. Psychopharmacol. 2003b; 23, 328–335. 11 Kropp S, Grohmann R, Hauser U, Ruther E, Degner D. Hyperglycemia associated with antipsychotic treatment in a multicenter drug safety project. Pharmacopsychiatry 2004; 37: S79-S83 Suppl. 1. 12 Hedenmalm, K., Hagg, S., Stahl, M., Mortimer, O., Spigset, O., Glucose intolerance with atypical antipsychotics. Drug Safety 2002; 25, 1107– 1116.