Characteristic | Garber 2006 | Goldberg 2005 | Hanefeld 2007 | Hällsten 2002 | Jung 2005 |
Intervention 1 (I1) / intervention 2 (I2) / control 1 (C1) | I1: rosiglitazone + metformin C1: glibenclamide + metformin | I1: pioglitazone C1: rosiglitazone | I1: rosiglitazone 4 mg + placebo I2: rosiglitazone 8 mg + placebo C1: glibenclamide + placebo | I1: rosiglitazone I2: metformin C1: placebo | I1: rosiglitazone + glimipiride C1: metformin + glimipiride |
Randomised controlled clinical trial (RCT) | Y | Y | Y | Y | Y |
Non‐inferiority / equivalence trial | N | N | Y | N | N |
Controlled clinical trial | N | N | N | N | N |
Design: parallel study | Y | Y | Y | Y | Y |
Design: crossover study | N | N | N | N | N |
Design: factorial study | N | N | N | N | N |
Crossover study: wash‐out phase | NA | NA | NA | NA | NA |
Crossover study: carryover effect tested | NA | NA | NA | NA | NA |
Crossover study: period effect tested | NA | NA | NA | NA | NA |
Method of randomisation | ? | stratified for being previously treated with oral antidiabetic drugs and according to sex | ? | ? | ? |
Unit of randomisation (individuals, cluster ‐ specify) | individuals | individuals | individuals | individuals | individuals |
Randomisation stratified for centres | ? | N | ? | ? | ? |
Randomisation ratio | 1:1 | 1:1 | 1:1:1 | 1:1 | 1:1 |
Concealment of allocation | ? | ? | ? | ? | ? |
Stated blinding (open; single, double, triple blind) | double‐blind | double‐blind | double‐blind, double‐dummy | double‐blind | ? |
Actual blinding: participant | Y | ? | Y | Y | NA |
Actual blinding: caregiver / treatment administrator | ? | ? | ? | ? | NA |
Actual blinding: outcome assessor | ? | ? | ? | ? | NA |
Actual blinding: others | ? | ? | ? | ? | NA |
Blinding checked: participant | N | N | N | N | NA |
Blinding checked: caregiver / treatment administrator | N | N | N | N | NA |
Primary endpoint defined (power calculation) | Y | Y | Y | N | N |
[n] of primary endpoint(s) | 1 | 1 | 1 | ? | ? |
[n] of secondary endpoints | 7 | 16 | 13 | ? | ? |
Total [n] of endpoints | 8 | 17 | 14 | 13 | 10 |
Prior publication of study design | N | N | N | N | N |
Outcomes of prior/current publication identical | NA | NA | NA | NA | NA |
Power calculation | Y | N | Y | N | N |
[n] participants per group calculated | 150 | NA | ? | NA | NA |
Non‐inferiority trial: interval for equivalence specified | NA | NA | Y | NA | NA |
Intention‐to‐treat analysis (ITT) | Y | Y | Y | ? | ? |
Per‐protocol‐analysis | N | Y | ? | ? | ? |
ITT defined | Y | Y | Y | NA | NA |
Missing data: last observation carried forward (LOCF) | ? | Y | Y | N | N |
Missing data: Other methods | N | N | N | N | N |
LOCF defined | NA | N | N | NA | NA |
Analysis stratified for centres | N | N | ? | N | N |
[n] of screened patients (I1 / I2/ C1/ total) | total: 356 | total: 4410 | total: 662 | ? | ? |
[n] of randomised participants (I1/ I2 / C1 / total) ‐ primary endpoint | I1: 158 C1: 160 total: 318 | I1: 369; C1: 366; total: 735 | I1: 200 I2: 191 C1: 207 total: 598 | I1: 15 I2: 16 C1: 14 total: 45 | I1: 15 C1: 15 total: 30 |
[n] of participants finishing the study (I1/ I2 / C1 / total) | I1: 133 C1: 131 total: 264 | I1: 299 C1: 286 total: 585 | I1: 153 I2: 158 C1: 173 total: 484 | I1: 14 I2: 13 C1: 14 total: 41 | I1: 14 C1: 13 total: 27 |
[n] of participants analysed (I1/ I2 / C1 / total) ‐ primary endpoint | I1: C1: total: 305 | I1: 363 C1: 356 total: 719 | I1: 195 I2: 189 C1: 202 total: 586 (ITT population) | I1: 14 I2: 13 C1: 14 total: 41 | I1: 14 C1: 13 total: 27 |
Description of discontinuing participants | N | Y | Y | N | N |
Drop‐outs (reasons explained) | Y | Y | ? | N | Y |
Withdrawals (reasons explained) | Y | Y | Y | Y | N |
Losses‐to‐follow‐up (reasons explained) | ? | Y | ? | N | N |
[n] of participants who discontinued (I1/ I2 / C1 / total) | I1: 25 C1: 29 total: 54 | I1: 70 C1: 80 total: 150 | I1: 47 I2: 33 C1: 34 total: 114 | I1: 1 I2: 3 C1: 0 total: 4 | I1: 1 C1: 2 total: 3 |
[%] discontinuation rate (I1/ I2 / C1 / total) | I1: 16 C1: 18 total: 17 | I1: 19 C1: 22 total: 20 | I1: 23.5 I2: 17.3 C1: 16.4 total: 19 | I1: 7 I2: 19 C1: 0 total: 9 | I1: 7 C1: 13 total: 10% |
Discontinuation rate similar between groups | N | Y | N | ? | Y |
[%] crossover between groups | ? | ? | ? | ? | ? |
Differences [n] calculated to analysed patients | N | NA | ? | NA | NA |
Adjustment for multiple outcomes / repeated measurements | N | N | N | N | N |
Baseline characteristics: Clinically relevant differences | Y 9% more men in I1 than C | N | N rosiglitazone 8 mg less male participants) | ? HbA1c not included in baseline characteristics | ? HbA1c and resistin not included in baseline characteristics |
Treatment identical (apart from intervention) | Y | Y | Y | Y | Y |
Compliance measured | N | N | N | Y | N |
Other important covariates measured (specify) | N | N | N | N | N |
Co‐morbidities measured | N | Y | N | N | N |
Co‐medications measured | N | N | N | N | N |
Specific doubts about study quality | N | N | N | N | N |
Funding: commercial | Y | Y | Y | Y | N |
Funding: non‐commercial | ? | ? | N | Y | Y |
Publication status: peer review journal | N | Y | Y | Y | N |
Publication status: journal supplement | N | N | N | N | N |
Publication status: abstract | N | N | N | N | N |
Publication status: other | N | N | N | N | N |
Notes | commercial funding not explicitly stated but three of five authors from pharmaceutical company | no quantitative data on adverse events | sample size not reported, LOCF parameter unclear, baseline no of participants 587 | patients received written diet instructions | poor reporting on quality criteria |
Footnotes Y = yes; N = no; ? = unclear I = intervention; C = control; (baseline) = if numbers for certain features could ne be derived from the text, numbers from baseline characteristics were used |