Summary of most often used outcome measures except smoking and their results
| Outcome | Instrument | Study identifier (author, year, first page No; see table A on bmj.com for references) | Design | Significance level* |
|---|---|---|---|---|
| Depression | Centre for Epidemiological Studies depression scale (CES-D) | Barrera 2002-McKay 2002 | RCT | NS |
| Bass 1998-Casper 1995-Brennan 1995-McClendon 1998 | RCT | NS | ||
| Brennan 1998-489 | RCT | Not reported | ||
| Glasgow 2003-410 | RCT | NS | ||
| Houston 2002-2062 (“pure” peer to peer intervention) | Cohort study | P<0.05† | ||
| Lieberman 2003-920 (“pure” peer to peer intervention) | Before and after study | P<0.001‡ | ||
| McKay 2001-1328 | RCT | NS | ||
| Tate 2001-1172 | RCT | Not reported | ||
| Tate 2003-1833 | RCT | Not reported | ||
| Winzelberg 2003-1164 | RCT | P<0.01† | ||
| Beck depression inventory | Quick 1999-Thesis (“pure” peer to peer intervention) | Before and after study | NS | |
| Medical outcome survey | Gustafson 1999-1 | RCT | NS | |
| Social support | Modified 6 items from interpersonal support evaluation list (ISEL) | Barrera 2002-McKay 2002 | RCT | P<0.05† |
| Instrumental and expressive social support (IESS) scale | Bass 1998-Casper 1995-Brennan 1995-McClenndon 1998 | RCT | NS | |
| 4 item social support scale adapted from multidimensional scale of perceived social support (MPSS) | Celio 2000-650 | RCT | NS | |
| 5 point scale developed by the authors | Gustafson 1999-1 | RCT | P<0.05‡ | |
| 6 item social support scale | Gustafson 2001-435 | RCT | P<0.01† | |
| “Perceived support from friends and relatives” | Hamman 2002-Thesis (“pure” peer to peer intervention) | Before and after study | NS | |
| “Number of peer contacts initiated by group members” | Harvey-Berino 2002-103 | RCT | NS | |
| Perceived social support-friends scale | Hazzard 2002-69 | Controlled clinical trial | P<0.05† | |
| Medical outcomes study social support survey | Houston 2002-2062 (“pure” peer to peer intervention) | Cohort study | NS | |
| “Increased perception of support from peers” | Johnson 2001-E24 | Before and after study | P<0.05‡ | |
| Perceived social support scale | Lacoursiere 2003-Thesis | Controlled clinical trial | NS | |
| Online social support scale | Zabinski 2001-129 | Before and after study | Not reported | |
| Healthcare use | Fewer phone calls to doctors | Alemi 1996-32 | Controlled clinical trial | P<0.05† |
| More phone calls to providers | Gustafson 1999-1 | RCT | P<0.05† | |
| Visits to emergency departments | Gustafson 1999-1 | RCT | NS | |
| Non-emergency visits | Gustafson 1999-1 | RCT | NS | |
| Shorter duration of hospital visits | Gustafson 1999-1 | RCT | P<0.05† | |
| Fewer hospital admissions during intervention | Gustafson 1999-1 | RCT | P<0.05† | |
| Doctor's Visits | Lorig 2002-792 | RCT | NS | |
| Eating disorder | Eating disorder examination questionnaire (EDE-Q) | Celio 2000-650 | RCT | P<0.01† |
| EDE-Q-weight/shape subscale | Winzelberg 1998-339 | RCT | NS | |
| Winzelberg 2000-346 | RCT | NS | ||
| Zabinski 2001-401 | RCT | NS | ||
| Zabinski 2001-129 | Before and after | P<0.05‡ | ||
| Eating disorder inventory (EDI) drive for thinness subscale | Celio 2000-650 | RCT | P<0.05† | |
| Winzelberg 1998-339 | RCT | NS | ||
| Winzelberg 2000-346 | RCT | P<0.05† | ||
| Zabinski 2001-401 | RCT | NS | ||
| Zabinski 2001-129 | Before and after study | P<0.05‡ | ||
| EDI bulimia subscale | Winzelberg 1998-339 | RCT | NS | |
| Winzelberg 2000-246 | RCT | NS | ||
| Zabinski 2001-401 | RCT | NS | ||
| Zabinski 2001-129 | Before and after study | NS | ||
| Body mass index (BMI) | Winzelberg 1998-339 | RCT | NS | |
| Zabinski 2001-401 | RCT | NS | ||
| Zabinski 2001-129 | Before and after study | NS | ||
| Weight loss | Body weight | Harvey-Berino 2002-103 | RCT | NS |
| Harvey-Berino 2002-1254 | RCT | P<0.05†§ | ||
| Tate 2001-1172 | RCT | P<0.05† | ||
| Tate 2003-1833 | RCT | P<0.05ঠ| ||
| Diabetes control | Glycosylated haemoglobin | Barrera 2002-McKay 2002 | RCT | NS |
| Glasgow 2003-410 | RCT | NS | ||
| Hamman 2002-Thesis (“pure” peer to peer intervention) | Before and after study | NS | ||
| lafusco 2000-1853 (“pure” peer to peer intervention) | Before and after study | P<0.001‡ |
For a complete list of all outcome measures and their results see table C on bmj.com.
All P values refer to a within group comparison (before and after a peer to peer intervention or complex intervention with peer to peer component) or a between group comparison between an arm with peer to peer intervention or complex intervention and an arm without peer to peer intervention or complex intervention. A significant finding usually means significant differences in favour of a peer to peer intervention (or intervention with peer to peer component), unless otherwise indicated.
↵* NS=non-significant at P<0.05 level.
↵† Differences between groups for randomised controlled trials, controlled clinical trials, cohort studies.
↵‡ Differences within groups (before and after, person to person intervention).
↵§ Favouring face to face support over internet group.
↵¶ When considering control group (peer to peer support) as before and after design.