27. Safety: gait disturbances.
| Study ID and design | Population | Outcome definition | Exposure MMR/MMRV vaccine | Findings | Crude data | Estimate (95% CI) |
|
db‐Miller 2005 Self‐controlled case series |
Children hospitalised with gait disturbance between April 1995 and June 2001 (n = 127, age 12 to 24 months). Children with gait disturbance resulting from general practice visit General Practice Research Database. (GPRD archive), born between 1988 and 1997 (n = 1398, age 12 to 24 months) |
(a) Hospitalisation for gait disturbance Review of hospital computerised records (April 1995 to June 2001, children aged 12 to 24 months) with ICD‐10 diagnoses related to acute gait disorder (G111, G112, G25, R26, R27, R29, H55, and F984). Cases were grouped into 5 categories, as follows: (1) presumptive viral/postviral ataxia (clinical history of ataxia and evidence of encephalomyelitis or cerebellitis with lymphocytosis in CSF or encephalographic changes); (2) probable postviral ataxia (history consistent with ataxia but CSF/other investigations inconclusive or not done and no other cause identified); (3) probably not postviral gait disturbance (vague symptoms not suggestive of cerebellar ataxia, e.g. unsteady gait associated with constipation or gastroenteritis); (4) non‐ataxic, non‐viral gait disturbance (including limp after trauma, septic bone or joint disease, unsteadiness following drug ingestion); (5) transient synovitis/‘‘irritable hip’’ (a transient condition described following viral illnesses and with no long‐term sequelae) ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ (b) GP visits for gait disturbance For the analysis of gait disorders presenting in general practice, information on all children born from 1988 to 1997 with at least 2 years of continuous follow‐up from birth in a GPRD practice deemed as supplying data of research standard was obtained from the Office for National Statistics. Read and OXMIS codes that indicated a consultation for possible gait disturbance in children aged 12 to 24 months were identified by mapping to ICD‐9 codes and by searching on the following keywords: ataxia, gait, co‐ordination, mobility, movement. Read/OXMIS descriptive diagnoses cover a wide range, so were grouped into 6 categories for analysis: (A) ataxia (including cerebellar ataxia and ataxic gait); (B) unsteady/veering/shuffling gait; (C) gait abnormality ‐ unspecified; (D) limp/limping gait; (E) poor mobility; (F) abnormal /involuntary movements. |
MMR vaccine: not reported (a) Risk period: after immunisation (a1) 0 to 30 days (a2) 31 to 60 days (a3) 0 to 60 days (b) Risk period after immunisation (b1) 0 to 5 days (b2) 6 to 30 days (b3) 31 to 60 days (b4) 6 to 60 days |
Conclusion: this study provides no evidence that MMR vaccine causes acute ataxia or other gait disturbance and suggests that the cases observed were chance occurrences, reflecting background incidence. The increased incidence of consultation for any gait disturbance 0 to 5 days after MMR vaccination was attributable to an excess in categories of gait disturbance (B, unsteady; and C, unspecified) that was caused by a clear excess of consultations on the day that MMR was given. It is biologically implausible that any specific MMR effect would be manifest on the day of vaccination since the viraemia induced by the vaccine, which might produce symptoms, does not start until the end of the first week. |
Hospitalisation for gait disturbance any (categories 2, 3, 5) n = 62 (a1) cases = 3 (a2) cases = 1 (a3) cases = 4 GP visits for gait disturbance All cases ((A) to (F)) (b1) cases = 31 (b2) cases = 69 (b3) cases = 102 (b4) cases = 171 |
rr (95% CI) (*) (a1) 0.83 (0.24 to 2.84) (a2) 0.20 (0.03 to 1.47) (a3) 0.46 (0.16 to 1.35) ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ (b1) 1.88 (1.30 to 2.72) (b2) 0.90 (0.70 to 1.17) (b3) 0.95 (0.77 to 1.19) (b4) 0.93 (0.78 to 1.12) (*) Poisson regression |
CI: confidence interval CSF: cerebrospinal fluid GP: general practitioner GPRD: General Practice Research Database ICD: International Classification of Diseases incidence: cases/PT MMR: measles, mumps, rubella vaccine MMRV: measles, mumps, rubella, and varicella vaccine OXMIS: Oxford Medical Information Systems PT: person‐time rr: rate ratio (relative incidence, incidence rate ratio)