Table 1. Characteristics of the studies included in the meta-analysis.
| Firstauthor | Year | Country | Ethnicitygroup | Genotyping method | Genotype | Definition | Controlsource | Cases | Controls | Male (%) | Age, year | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cases | Controls | Cases | Controls | ||||||||||
| Bessa [18] | 2009 | Egypt | African | Multiplex PCR | GSTM1GSTT1 | SBP ≥140 mm Hg, DBP ≥90 mmHg, and/or a history of hypertension | PB | 40 | 40 | 28 (70) | 25 (62.5) | 54.3 ± 5.6 | 52.1 ± 6.3 |
| Borah[19] | 2011 | India | Asian | Multiplex PCR | GSTM1GSTT1 | SBP ≥140 mm Hg, DBP ≥90 mmHg, or under antihypertensive medication | PB | 223 | 236 | 83 (37.2) | 94 (39.3) | 37.5 ± 12.5 | 36.6 ± 11.9 |
| Capoluongo[20] | 2008 | Italy | Caucasian | PCR | GSTM1GSTT1 | SBP ≥140 mm Hg, DBP ≥90 mmHg, or were receiving any of the antihypertensive medications | PB | 255 | 99 | 82 (32.1) | 36 (36.3) | 85.4 ± 4.6 | 87.0 ± 5.3 |
| Hussain [22] | 2012 | United ArabEmirates | Asian | Multiplex PCR | GSTM1GSTT1 | SBP ≥140 mm Hg, DBP ≥90 mmHg, or current use of anti-hypertensive medication | HB | 30 | 33 | NA | NA | 40.1 ± 14 | 41.7 ± 13.6 |
| Marinho [25] | 2006 | Portugal | Caucasian | Multiplex PCR | GSTM1GSTT1 | NA | PB | 94 | 207 | 57 (60.6) | NA | 67.4 ± 10 | 52.6 ± 12 |
| Oniki [27] | 2008 | Japan | Asian | PCR | GSTM1GSTT1 | SBP ≥140 mm Hg, DBP ≥90 mmHg, and/or a history of hypertension | PB | 130 | 338 | 100 (76.9) | 226 (66.8) | 56.4 ± 8.4 | 52.0 ± 9.1 |
| Polimanti [28] | 2011 | Italy | Caucasian | Multiplex PCR | GSTM1GSTT1 | Based on the physician’s diagnosis and on the use of antihypertensive medications | PB | 193 | 210 | 80 (41.5) | 74 (35.2) | 58.7 ± 0.7 | 57.6 ± 0.8 |
| Turkanoglu [29] | 2010 | Turkey | Caucasian | Multiplex PCR | GSTM1GSTT1 | SBP ≥140 mm Hg, DBP ≥90 mmHg, and/or use of antihypertensive drugs | HB | 150 | 127 | NA | NA | 35–90 | 35–90 |
| Lee [24] | 2012 | Korea | Asian | Multiplex PCR | GSTM1GSTT1 | SBP ≥140 mm Hg, DBP ≥90 mmHg | PB | 258 | 497 | NA | NA | NA | NA |
| Wang [30] | 2012 | China | Asian | PCR | GSTM1GSTT1 | NA | PB | 323 | 202 | NA | NA | NA | NA |
| Yang [31] | 2004 | Taiwan | Asian | Multiplex PCR | GSTM1GSTT1 | NA | HB | 475 | 230 | 241 (50.7) | 110 (47.8) | NA | NA |
| Miranda-Vilela [26] | 2010 | Brazil | Mixed | PCR | GSTM1GSTT1 | SBP ≥140 mm Hg, DBP ≥90 mmHg | PB | 91 | 110 | 46 (50.5) | 54 (49.1) | 50.5±1.2 | 50.6±01.2 |
| Jiang [23] | 2010 | USA | Mixed | PCR | GSTM1GSTT1 | History of hypertension, medication use | HB | 278 | 812 | NA | NA | 25–64 | 25–64 |
| Cruz-Gonzalez [21] | 2009 | Spain | Caucasian | PCR | GSTM1 | SBP ≥140 mm Hg, DBP ≥90 mmHg | PB | 281 | 110 | 120 (42.7) | 51 (46.4) | 64.1 | 63.4±15.7 |
Abbreviations: BMI: body mass index; DBP: diastolic blood pressure; GSTM1: glutathione S-transferase M1; NA: not available; GSTT1: glutathione S-transferase T1; HB: hospital based; PB: population based; PCR: polymerase chain reaction; SBP: systolic blood pressure; SD: standard deviation.