Table 6.

Prognostic studies conducted in LMIC or disadvantaged populations.

Author	Year of publication	Country region	Study design	Participants	Age	Diagnostic methods	Study question	Study period	Results	Comments
Yen	2015	Taiwan	Retrospective cohort, register study	10248 diagnoses with COM		ICD codes in Taiwan’s national health insurance program (covers 98% of population)	what is the risk of developing sudden SNHL if you have COM	2001–2008	Incidence of sudden sensorineural HL (sSNHL) was 3 times higher among pt’ens with COM compared to age and sex matched control group. The risk of sSNHL was 101/10248 among COM = 0,01 and non-COM 103/30744 = 0,003	Large population, Side of COM and later sSNHL was not included. The relative risk is higher but the absolute risk is still small.
Yehudai	2015	Israel	Tertiary centre, retrospective, preoperative audiograms, for COM or cholesteatoma. normal ear BC vs COM ear BC.	124 with unilateral COM	7–18	otomicroscopy, audiometry 500–4000 Hz	Is SNHL in COM ears clinically significant, and what are the risk factors	1997–2012	Difference in mean BC at 1000, 2000 and 4000 Hz, 1.3 dB 4.3 dB and 7.2 dB. Statistically significant meaning COM ear showed SNHL compared to the healthy ear. Age >10 and presence of cholesteatoma increased the risk of SNHL	Small difference within the insecurity of an audiogram, maybe not clinically significant finding. The postop BC could have been evaluated too.
Orji	2015	Nigeria	retrospective, register, tertiary centre	203 CSOM cases from 2009 to 10 compared with 343 cases from 1990 to 91	mean age 27 and 21 years	otoscopy	incidence of CSOM at the centre, complication rate	1990–2010	CSOM incidence lowered, cases tended to be older, fewer intracranial complications in newest time period, but overall complication rate unchanged
Touati	2015	Morocco	retrospective case series, tertiary centre,	30	9–15 years	otoscopy, otomicroscopy?	describe COM with cholesteatoma, clinical and presentations and surgical intervention	jan 2009 to 2013	86% had conductive HL, 60% had airbone gap over 30 dB
Peñaranda	2015	Colombia different regions	school based	1526	5–14	otoscopy, audiometry	prevalence of AOM, perforation, sequelae, HL		Perforation variation between regions and races from 0 to 1.4%. Variation in sequelae and conductive HL	Demonstrates challenges in OM prevalence in countries with large differences in access to healthcare and racial heterogeneity
Maile	2015	Nepal	questionnaire	242	all ages	Glasgow health Status Inventory and Glasgow benefit inventory	Adapt QOL instruments to Nepal. Quantify burden of disease. Determine QoL alterations associated with surgery for CSOM or Cholesteatoma.	2012–2013	CSOM associated with reduced QoL, same degree as cholesteatoma. Surgical intervention is associated with increased QoL
Penido	2015	Brazil	retrospective register, case series tertiary centre	51	mean 31 years	Unclear for ear examination, but imaging modalities were available. CT; MR, MRA	describe epidemiological aspects of OM related ICC (intracranial complication)		80% of complications were due to COM while 20 % were due to AOM. 4 died to ICC. Mean age ICC from AOM 30 years, but bifasic (majority under 15 or over 60) mean age icc from CSOM was 26 years. Mean time of hospitalization was 34 days permanent neurological sequelae were seen in 29% of all ICC cases. 4 patients died
Avsntorp	2016	Greenland	follow-up on population based cohort	223 children	4–10 years	Video-otoscopy, tympanometry, audiometry	prevalence of CSOM and OM related hearing loss	2010	5.8% CSOM, 13.9% OME, 55% sequelae. CSOM median PTA high/low 34/31 dB, OME 23/23, normal ears 12/13 dB	High prevalence of CSOM, 1 case meningitis, mental retardation and bilateral severe HL.
Maranhão	2016	brazil	retrospective case series, register based, tertiary centre	14 pts labyrinthitis secondary to OM	mean 40		clinical factors and hearing level among pt’ens with OM related labyrinthitis	1987–2013	43% had cholesteatoma, 43% AOM 14% had CSOM associated with facial paralysis, meningitis. Intracranial abscess, one death
Poole	2016	Nepal	questionnaire, case-control	N = 153. 82 non-OM vs 71 CSOM/AOM/HL recruited from waiting room health care centre	mean 39 vs 48 years	history of OM	Investigate knowledge, beliefs, attitude and practice regarding CSOM and HL		Interestingly 70 % responded that people with HL were discriminated in society
Zaidi	2016	Pakistan	Case series (described as cross sectional?) tertiary centre	CSOM	6–45 years	audiometry average of 3 speech frequencies, bone conduction?	What is the frequency of SNHL in CSOM	2013–2014	52% had SNHL	frequencies not reported, use of bone conduction not reported
Mushi	2016	Tanzania	prospective cross sectional tertiary centre	301 CSOM cases with 6 weeks otorrhoea	All over 1 year	otoscopy and tuning fork tests, cultures. HIV tests	find predictors of complications in CSOM, evaluate treatment outcome and anti-microbiological susceptibility	2013–2014	Majority of patients with prolonged illness duration, otalgia, infected with multi drug resistant bacteria and those with positive HIV status poorly respond to treatment and tend to present with disease complications	632 attends the clinic annually. 48% of patients present with CSOM at the clinic
Mushi	2016	Tanzania	Case series, tertiary centre	410 CSOM cases	Median age 29.5 in cases with fungi. Age not stated in overall group		Prevalence of fungal infection		44 (11%) of cases had fungi	There was an association but not significant between co-infection with fungi and poor treatment outcome. Causality cannot be established. High risk of bias
Dobriansky	2017	Brazil	Cross-sectional, register. Tertiary centre	158 patients. 98 CSOM with otorrhoea and contralateral normal ear. 60 CSOM with dry perforation	median 26 years in otorrhoea group, unknown range	otoscopy, audiometry	is otorrhoea associated with SNHL		otorrhoea is associated with SNHL
Jensen PV	2017	Zimbabwe	case report	1 fatal	8				fatal complication to AOM Gradenigo syndrome. Lethal outcome due to inaccessibility diagnosis and treatment
Toros	2017	Turkey	case	1	45 years	otoscopic			mastoiditis, bezold, paraspinal abscess, sinus thrombosis. Survived with hemiparesis	first description of paraspinal abscess due to OM
Qin	2017	China	case report	1	10 year				Zygomatic root abscess and fistula, after 6 months of low grade infection
Singh	2017	India	prospective case series tertiary centre	46 CSOM/cholesteatoma patients	7–50	otomicroscopy, surgery	Occurrence of fungal infection		All had otorrhoea, 43% had fungal co-infection, 15% extra-cranial complications, no intracranial complications	Causal relation between chronic otorrhoea and fungal infection cannot be established. Highlights the importance of testing for fungal infection in recalcitrant cases. Prevalence rates are very high, high risk of selection bias. Authors hypothesis that it could be due to increased availability of AB in India
Kameswaran	2017	India, Tamil nadu	case series, tertiary centre	502 patients undergoing tympanoplasty with mastoidectomy		otomicroscopy, surgery, CT		2011–2012	25 (5%) patients had M tuberculosis in ear samples. Authors suspect TB OM to be under reported in India	tuberculous otitis media higher risk of complications due to delayed diagnosis as many patient dońt have coincident pulmonary symptoms. More severe hearing loss and presence of complication.
Cordeiro	2018	Brazil	Prospective case series with follow-up. Tertiary centre.	82 with AOM at first visit .41 followed- up	5–65, median 38 years	Extended high frequency audiometry 8 to 16 KHz. Otoscopy, tympanometry	impact of first episode of AOM on hearing after 14,28,49 and 180 days	2015–2016	First OM episode led to high frequency elevated thresholds at 6 months follow-up in the affected ear. At 14 days follow-up standard audiometry did not show any HL
Singh	2018	India	case				description of case		tuberculosis middle ear, mastoid, zygomatic and Bezold abscess	tuberculosis OM pathogen in India
Jones	2018	Australia	semi-structured interviews	9 caregivers to 12 children with bilateral OM, some with CSOM, participating in a program speech, language, hearing loss and school readiness		Medical history	what is the parents view on the program.		Parents were positive towards the program for various reasons. Parents ranked OM as the highest health concern	The more OM concerned parents more likely to participate in the program. May not be representative for the community. High risk of bias. But only study that asked parents to rank “burden of disease”
Singer	2018	Egypt	prospective, case series (patient own control) tertiary centre	200 unilateral CSOM, using contralateral as control-ear	10–60	Otomicroscopy, tympanometry audiometry 500–4000. BC average 25 dB or	occurrence of SNHL in CSOM	2016–2017	10 % had SNHL, CSOM associated with SNHL but other predisposing factors e.g.