Table 2b.
Summary of results and potential for bias of articles published on the effectiveness of community-based control strategies aimed at reducing porcine cysticercosis.
| Country [reference] |
Results | Limitations | |||||
|---|---|---|---|---|---|---|---|
| Information bias | Confounding | Selection bias | Clustering / non independence |
Power/ generalizability |
Other | ||
| Mexico [11] |
Antibodies (EITB): Pre: 4.8%; 6 mo.: 2.2%; 42 mo.: 3.4% PPR (6 mo): 0.46 (95%CI: 0.21-1.04) PPR (42 mo): 0.70 (95%CI : 0.32-1.53) Tongue examination: Pre: 1.2%; 6 mo.: 1.1%; 42 mo.: 0.6% PPR (6 mo): 0.90 (95%CI: 0.30-2.73) PPR (42 mo): 0.48 (95%CI : 0.10-2.26) |
Low: Valid test | High: not controlled, no randomization |
High: Sampling not described |
Ignored / ignored | Poor / poor | More pigs were sampled at 6 mo., followed by 42 months without any explanation. |
| Guatemala [12] |
Antibodies (EITB) : Pre: 55%; Post: 7% PPR: 0.13 (95%CI: 0.09-0.20) |
Low : Valid test | High: not controlled, no randomization |
Low : Pigs randomly sampled |
Ignored / ignored | Poor / poor | Pigs sampled post intervention were younger. |
| Mexico [21] |
Tongue inspection (sentinel pigs) : Pre: 13.8%; 14 mo: 12%; 28 mo: 16% PPR (14 mo): 0.87 (95%CI: 0.33-2.33) PPR (28 mo): 1.16 (95%CI : 0.38-3.52) |
High: Poor test (especially for decreasing number of cysts) |
High: Not controlled, no randomization |
Moderate: Variation in sample size in the 3 examinations unexplained |
Ignored / ignored | Poor / poor | Poorly designed and analyzed study. |
| Mexico [17] |
Tongue inspection Pre (6 villages): 25.8%; (4 villages): 2.0%; 12 mo (6 villages): 12.5%; 24 mo (4 villages): 0.5% PPR (12 mo): 0.48 (95%CI: 0.24-0.98) PPR (24 mo): 0.23 (95% CI: 0.64-0.84) |
High: Poor test | High: Not controlled, no randomization |
High: Choice of villages to follow-up unexplained |
Ignored / ignored | Poor / poor | Poorly designed study |
| Peru [18] |
Antibodies (EITB) using incident cases: ±OR (treatment): 1.28 (0.59; 2.78) OR (post period): 2.84 (0.79; 10.25) OR (treatment and post period): 0.39 (0.18-0.81) |
Moderate: Contamination of intervention, valid test |
Moderate: Randomization broken (imbalance in baseline prevalences) |
Moderate: Census of all pigs; important losses to follow- up |
Unclear (GEE used, but village- effects included)/ only new cases or different pigs included |
Moderate / good for that area |
Inappropriate statistical analysis (logistic regression for common outcome- overestimates magnitude of effect; model mis-specified) |
| Mexico [16] |
Tongue examination: Pre: 6%; Post: 11% *PPR : 1.86 (95%§CI : 1.14-3.05) |
High: poor test | High: not controlled, no randomization |
High: Sampling not described |
Ignored / ignored | Poor / poor | Methods inconsistent with results description. |
| Tanzania [9] |
Antigens (AgELISA): ¶IRR = 0.57 (95%BCI: 0.3-1.0) |
Low; Valid test | Low: randomized and adjusted for baseline prevalence |
Moderate: High losses to follow- up |
Evaluated not needed / only new cases included |
Good / areas similar to Mbulu district |
Short follow-up of 2- 9 months. |
| Mexico [13] |
Antibodies (EITB) : Pre: 5.2%; Post: 1.2% PPR: 0.24 (95% CI : 0.05; 1.06). |
Low: Valid test | High: not controlled, no randomization |
High: Sampling not described |
Ignored / ignored | Poor / poor | |
| Ecuador [20] |
Inspection at Slaughterhouse: Pre : 11.4%; Post : 2.6% PPR : 0.23 (0.06-0.85) |
High: Poorly described method |
High: not controlled, no randomization |
High: Sampling not described |
Ignored / ignored | Poor / poor | Fewer infected pigs may have been sent to the slaughterhouse after education. |
| Mexico [27] |
Antibodies (AgELISA): Pre: 17.7%; Post: 13.3% PPR: 0.75 (0.50-1.11) Tongue inspection: Pre: 7.0%; Post: 0.5% PPR: 0.07 (0.02-0.29) Ultrasound: Pre: 3.6%; Post: 0.3% PPR: 0.07 (0.01-0.54) |
High : Poor tests | High : not controlled, no randomization |
High: large losses to follow-up; sampling not described |
Ignored / Ignored | Poor / poor | Poorly described methods; errors in calculation in the Tables and in p- values reported |
*
PPR: Prevalence Proportion Ratio
§
CI : Confidence Interval
¶
IRR: Incidence Rate Ratio
±
OR: Odds Ratio
GEE: Generalized Estimating Equations
EITB: Enzyme linked immunoelectrotransfer blot assay to detect antibodies to T. solium
AgELISA : Enzyme linked Immunosorbent assay to detect antigens to T. solium