| Characteristic | Goke 2002 | Goldberg 2005 | Hanefeld 2004 | Jovanovic 2004 | Langenfeld 2005 |
| I1: pioglitazone C1: acarbose | I1: pioglitazone C1: rosiglitazone | I1: pioglitazone + sulfonylureas C1: metformin + sulfonylureas | I1: pioglitazone C1: repaglinide C2: repaglinide + pioglitazone | I1: pioglitazone C1: glimepiride | |
| Randomised controlled clinical trial (RCT) | Y | Y | Y | Y | Y |
| Non‐inferiority / equivalence trial | N | Y | N | N | N |
| Controlled clinical trial | N | N | N | N | N |
| Design: parallel, crossover, factorial RCT | parallel | parallel | parallel | parallel | parallel |
| 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 | computerized, telephone randomisation ‐ stratified for gender, 2 BMI classes and study centers in blocks of 4 | stratified for being previously treated with oral antidiabetic drugs and sex | ? | ? | ? |
| Unit of randomisation (individuals, cluster ‐ specify) | individuals | individuals | individuals | individuals | individuals |
| Randomisation stratified for centres | Y | ? | ? | ? | NA |
| Randomisation ratio | NA | NA | NA | 1:1:2 | NA |
| Concealment of allocation | ? | ? | ? | ? | ? |
| Stated blinding (open; single, double, triple blind) | open‐label | double‐blind | double‐blind | open‐label | open‐label |
| Actual blinding: participant | NA | ? | ? | NA | NA |
| Actual blinding: caregiver / treatment administrator | NA | ? | ? | NA | NA |
| Actual blinding: outcome assessor | ? | ? | ? | ? | Y |
| Actual blinding: others | NA | ? | ? | NA | NA |
| Blinding checked: participant | NA | ? | ? | NA | NA |
| Blinding checked: caregiver / treatment administrator | NA | ? | ? | NA | NA |
| Primary endpoint defined | N | Y | Y | Y | N |
| [n] of primary endpoint(s) | 1? | 1 | 1 | 1 | 1 |
| [n] of secondary endpoints | 9 | 16 | 11 | 6 | 12 |
| Total [n] of endpoints | 10 | 17 | 12 | 7 | 13 |
| Prior publication of study design | N | N | N | N | N |
| Outcomes of prior / current publication identical | NA | NA | NA | NA | NA |
| Power calculation | N | N | N | Y | N |
| [n] participants per group calculated | NA | NA | NA | ? | NA |
| Non‐inferiority trial: interval for equivalence specified | NA | NA | NA | NA | NA |
| Intention‐to‐treat analysis (ITT) | Y | ? | Y | ? | ? |
| Per‐protocol‐analysis | Y (HbA1c) | ? | ? | ? | Y |
| ITT defined | N | ? | Y | NA | NA |
| Missing data: last‐observation‐carried‐forward (LOCF) | Y | Y | Y | N | N |
| Missing data: other methods | N | Y | N | imputed data by means of the incremental mean imputation (IMI) method | N |
| LOCF defined | N | N | Y | NA | NA |
| Analysis stratified for centres | ? | Y | ? | ? | NA |
| [n] of screened patients | 381 | 4410 | ? | ? | Total: 192 |
| [n] of randomised participants | I1: 129 C1: 136 Total: 265 | I1: 369 C1: 366 Total: 735 | I1: 319 C1: 320 Total: 639 | I1: 62 C1: 61 C2: 123 Total: 246 | I1: 89 C1: 84 Total: 173 |
| [n] of participants finishing the study | I1: 110 C1: 97 Total: 207 | I1: 299 C1: 286 Total: 585 | I1: 81.5% C1: 87.2% Total: >80% | I1: 26 C1: 36 C: 105 Total: 167 | I1: 81 C1: 81 Total: 162 |
| [n] of patients analysed for primary endpoint | I1: 129 C1: 136 Total: 265 | I1: 363 C1: 356 Total: 719 | I1: 319 C1: 320 Total: 639 | I1: 57 C1: 54 C2: 123 Total: 234 | I1: 89 C1: 84 Total: 173 |
| Description of discontinuing participants | Y | Y | Y | Y | Y |
| Drop‐outs (reasons explained) | Y | Y | Y | Y | Y |
| Withdrawals (reasons explained) | Y | Y | Y | Y | Y |
| Losses‐to‐follow‐up (reasons explained) | Y | Y | ? | ? | ? |
| [n] of participants who discontinued | I1: 19 C1: 39 Total: 58 | I1: 70 C1: 80 Total: 150 | I1: 62 C1: 41 Total: 103 | I1: 36 C1: 25 C2: 18 Total: 79 | I1: 8 C1: 3 Total: 11 |
| [%] discontinuation rate | I1: 14.7% C1: 28.7% Total: 21.9% | I1: 19.0% C1: 21.9% Total: 20.4% | I1: 19.5% C1: 12.8% Total: 16.1% | I1: 58.1% C1: 41.0% C2: 14.6% | I1: 9.9% C1: 3.6% Total: 6.8% |
| Discontinuation rate similar between groups | N | Y | N | N | N |
| [%] crossover between groups | C1 to I1: n=24 (24.7%) | ? | ? | ? | ? |
| Differences [n] calculated to analysed patients | NA | NA | NA | ? | NA |
| Adjustment for multiple outcomes / repeated measurements | N | N | N | N | N |
| Baseline characteristics: clinically relevant differences | N | N | N | N | N |
| Treatment identical (apart from intervention) | Y | Y | Y | Y | Y |
| Compliance measured | Y | N | N | N | Y |
| Other important covariates measured (specify) | N | N | N | N | N |
| Co‐morbidities measured | N | Y | N | N | N |
| Co‐medications measured | N | N | Y | N | Y |
| Specific doubts about study quality | Y | N | N | ? | N |
| Funding: commercial | Y | Y | Y | ? | Y |
| Funding: non‐commercial | N | N | N | ? | N |
| Publication status: peer review journal | Y | Y | Y | Y | Y |
| Publication status: journal supplement | N | N | N | N | N |
| Publication status: abstract | N | N | N | N | N |
| Publication status: other | NA | NA | NA | NA | NA |
| Notes | one‐sided statistical tests with alpha set at 2.5%; one companion publication | no quantitative data on adverse events | none | randomisation ratio not mentioned (data in table of baseline characteristics only) | unclear whether imputation methods were used for missing data; two companion publications |
| Symbols & abbreviations: Y = yes; N = no; ? = unclear I = intervention; C = control |
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